Physiology of color blindness with special reference to a case of deuteranopia

Transcription

1 University of Ioa Ioa Researh Online Theses and Dissertations 1915 Physiology of olor blindness ith speial referene to a ase of deuteranopia George Carter Albright State University of Ioa This ork has been identified ith a Creative Commons Publi Domain Mark 1.0. Material in the publi domain. No restritions on use. This thesis is available at Ioa Researh Online: Reommended Citation Albright, George Carter. "Physiology of olor blindness ith speial referene to a ase of deuteranopia." MS (Master of Siene) thesis, State University of Ioa, Follo this and additional orks at:

2 PHYSIOLOGY OP COLOR BLINDNESS WITH SPECIAL REFERENCE TO A CASE OF DEUTERANOPIA A Study Pursued by George Carter Albright, B. A., M.D. In partial fulfillment of the requirements for the degree, Master of Siene State University of Ioa

3 The funtion of the eye, as of any other organ in the human body, is first and foremost to enable the individual to live, and to live in harmony ith his surroundings. This funtion may be asribed to the eye of any animal that has developed to the point here the eye is a separate and distint organ. Whether or no the ability of the individual to go further and analyse the sensations that ome to him through the eye, applying to the differing sensations the terms that e are ont to all olor, is a proess of development of this or that part of the visual trats is for the present a matter of indifferene. The average human being does distinguish olor, and through years e have ome to apply to ertain sensations ertain names, and all those sensations ertain olors. What these are, e need not strive to define. Blue is blue, green is green, and the means hereby e distinguish blue from green are not knon. Theories have been advaned to explain, but they are only theories, or even more orretly hypotheses. Attention as direted, in the latter part of the eighteenth entury by Dalton, to the fat that some individuals aid not see olors the same as the majority of men did, he himself being so distinguished. Then a little later Neton demonstrated that hite light is made

4 2 up of a mixture of olors, of hih the average individual ould reognize six, some fe ould see seven, and still others ould see but four. To this latter lass those ho do not see olors as does the average individual, the term olor blind has been applied. Sine that time, thru numberless studies, it has been shon that about four per ent of males, and a fration of one per ent of females are olor blind; that there is a ertain regularity in the olors that these numbers are unable to see; and further that this dereased funtion is onfined fairly losely to families. The olor blind vary in the harater and amount of their olor blindness. There is an inability to see any olor, ahromatopsia. To suh the orld of olor is simply a series of blak and hite pitures. These are rare. Muh more ommon are those hose ability to see olors is diminished, the ondition of dyshromatopsia. This again is subdivided into the rare, those ho annot see blue and yello, and the ommon, those ho annot see red and green. In fat the existene of a true ondition of blue-yello blindness is questioned by some, and only a very fe, if any, ases have been reported. This leaves, then, olor blindness in the main to be a ondition of diminished ability to see red and green, or red or green. That is, one is muh more defiient than the other, for example, red poor and green is fairly good; or green is poor and red fairly good. Although the visible spetrum onsists of six or seven olors, there are only three fundamental, out of hih

5 3 by proper ombination, all the others an be made. These are red, green and blue. Yello also exists as a fundamental olor, but sine it an also be made by ombining red and green, it is not inluded in the three. Persons ho see all three of these olors sure said to be trihro- mates. Those ho see only to, ho are blind for one are dihromates. On examination of the spetrum by the normal person the range of olor from the red to the violet end extends for a ertain standard distane, measured in ave lengths of the light rays. The red-green blind are found to differ among themselves on examining the spetrum. To some it is shorter, and the portion of greatest brightness is found in the green (normal being the yello). These are alled protanopes. Others see the full length of the spetrum, the maximum brightness being in the yello, and these are knon as deuteran- opes. Color blindness is ongenital or aquired -the former due to some defet in parent, the latter to drugs or inflammatory onditions of retina or opti nerve(3). Whatever attempts are made to study these phenomena, all reognize that the problem is a physiologial one, one of funtion; and also that the seat of the differene in vision beteen the olor blind and normal is in the retina, not in the ortial enter. It is also ell knon that only ertain parts of the retina in the normal individual

6 4 sense olors, and that this olor sensing area is still further divided up into zones for ertain olors as ill be explained later. Anatomy of the Retina. The retina is the spread out terminal filaments of the opti nerve. It is a soft inelasti membrane, ompletely transparent during life exept for the blood stream in the vessels. It is made up of some nine layers, the only one of hih e are onerned ith being the outer layer, the rods and ones, lying next to the horoid of the eye. These are the sensing elements, and being outside, the rays of light in order to at upon them must traverse all the other layers from the vitreous out to the rods and ones. On eak magnifiation the rods and ones are seen to be a finely striated layer, ith its striations at right angles to the inner surfae of the horoid. On higher magnifiation this layer is seen to onsist of to elements; (a) the rods ith a length orresponding to the entire thikness of only about to mu., and (b) the ones, flask-form strutures that are muh shorter and thiker, not oupying the entire thikness of the layer. The exat form of the ones varies ith the loation, those at the fovea being long and slender like the rods, and those at the periphery muh shorter and thiker. The distribution of these to elements is of importane. Beginning at the foveola in the fovea e have an area aording to Fritsh (1 ) ith a diameter of 0.15 here only ones are to be found. Outside this field the rods appear, at first

7 5 sattering, then surrounding the individual ones as a irle. Cones and rods are found in the retina from the fovea outard in gradually hanging numbers, the rods inreasing, the ones dereasing, until at the periphery, near the ora serrata e have only rods. This arrangement of elements is important to remember in onnetion ith one of the prominent theories of olor blindness. In addition to this e find in the rods a substane that varies in amount oing to light and dark, knon as visual purple or rhodopsin. This substane is not found in the ones. It inreases in the rods in the dark, and bleahes out rapidly on being exposed to the light. This an be niely demonstrated in the frog b y exposing the dark adapted retina ith its visual purple to the light. Under proper onditions a photograph of an open indo ith ross bars an be obtained, the light bleahing the purple, the bars leaving it unaffeted (2). Although this substane is affeted by light, being deomposed by light and building up again in the dark, it is not to be thought that its deomposition is in any ay responsible for the sensation of light that the mind reeives. Animals that possess no visual purple have keen vision, and in the human eye the spot of keenest vision, namely, the foveola, has no rods and therefore no visual purple. Just hat is the differene in funtion beteen the rods and ones is not knon. Theories have been advaned that the rods see hite and blak only hile the ones see these and olors also, but

8 6 no definite proof is forthoming. From the fat, hoever, that e see ith those portions of the retina in hih only one of them an be found e kno that both have to do ith the sensation of sight. No histologial or pathologial hanges have ever been demonstrated in eyes that are olor blind, onsequently it is not knon that there are any suh. No differenes of distribution of the to have been observed in the eye of the olorblind as ompared ith the normal. In various times there have been a number of attempts made to explain the phenomena of olor vision. These attempts have been knon as theories, though it is not amiss to say that they are more properly simply hypotheses. None have sueeded in expalining all the fats of olor vision and blindness, nor do all of them taken together anser some of the fundamental questions involved, simply beause there is no method of experimental verifiation. Some of the leading theories follo. 1. The Young-Helmholtz Theory, This theory as proposed by Thomas Young in about 1807 (4) and as later added to by Helmholtz. It starts ith the assumption that there are three fundamental olor sensations, red, green and violet, to hih there ere three orresponding photo-hemial substanes. By the ation of olored light, say red, the red photohemial substane as dissoiated, the nerve impulse traveled along speial nerve fibers for red to the proper enter in

9 7 in the brain. In a similar ay the green substane as dissoiated ith green sensation that is arried along its on speial fibres to its on enter, different from that of red. Thus all three olor sensations are arried to their respetive enters in the brain, eah along its on path. White or gray light as seen by a proper ombination of the three fundamentals, or under ertain onditions to of them,- the omplementary olors, e.g., red and green. Blak as the result of an absene of any stimulation. Yello, blue and the other olors ere produed by the varying proportions of the three fundamentals. All three of the fundamental substanes ere ated upon by all the rays of the spetrum, but the red substane as affeted most by the rays of longest length, the red rays. This is made lear by the draing. 2. The Hering Theory. Like the young-helmholtz theory, the Hering Theory supposes three photohemial substanes of suh a nature as to give six different qualities of sensation. To qualities are seured from eah photohemial substane, one from the destrution or breaking don of the substane, alled disassimilation, the kataboli proess,

10 8 the other from the onstrution or building up of the substane, elled assimilation, the anaboli proess. The three fundamental olor substanes, aording to the Hering theory, are red-green, yello-blue, and hite-blak. In tabular form aording to Hoell these may be stated (5) thus: Photo-hemial substane Retinal Proess Sensation red-green disassimilation red assimilation green yello-blue disassimilation yello assimilation blue hite-blak disassimilation hite assimilation blak Aording to this theory the partially olor blind persons, for example, red-green blind, are so beause the red-green photohemial substane is laking. Blue-yello blind are so beause the blue-yello substane is laking. Total olor blindness ould be due to the absene of all four olor substanes, leaving only the hite and blak; and hene the orld ould be a series of hite and blak and gray pitures. He aounts for the formation of gray or hite by omplementary olors by this reasoning. The omplementary olorsubstanes are antagonisti, and if the proper ombination of any to suh be shon, they eah destroy the other, and the hite-blak substane present is stimulated by the light entering the retina to send the sensation of hite or gray to the onsiousness. All light rays, aording to this theory, disassoiate the hite-blak substane.

11 9 Hering's theory has to modifiations that are of importane in that they try to explain ertain defets of the original theory. proposed by Ebbinghaus. The first of these is the theory He (6) substitutes for the assimilative and disassimilative proesses of Hering, a "oneption of progressive and antagonisti stages of deomposition of three visual substanes. In partiular, Ebbinghaus makes the folloing suppositions; The rod pigment, alled the visual purple, by its first stage of deomposition oasions sensations of yello. In its seond phase this substane is yello, not purple, and its deomposition auses sensations of blue. There is a seond, an objetively red-green substane in the ones, and the first and seond proesses of its deomposition oasion the olors of red and green; it has never been observed beause in its green phase it is omplementary to the visual purple. A third hite-blak invisible substane oasions hite and blak by its progressive deomposition." There are ertain so vital objetions to this theory that it is not seriously onsidered. For example, the deomposition of these substanes is progressive. Hene they annot aount for a mixture of olors or the formation of shades and tints. What is a more vital objetion is that he assumes visual purple to be the substane essential to olor, a fat already shon above to be untrue. Further, if his theory ere true, to see green one ould first sense yello, then blue, and finally green. A seond modifiation of the theory of Hering is that

12 10 of Mueller. It is of muh greater importane in that it supplies a rational proess and one that is ell knon,- for an irrational priniple, knon in no other field: the priniple of assimilation ausing a sensation; physiologially an anomaly if not an impossibility. Mueller's theory is, that in plae of assimilation and disassimilation e have simply a reversible hemial proess going on in the photohemial substanes. Suh a oneption of the proess is muh more easily reoniled to knon fats of siene than is Hering's original idea. 3. The theory of Mrs. C. L. Franklin. In onnetion ith the Franklin theory must be mentioned the names of Koenig and Von Kries, ho agree ith Mrs. Franklin in so far as they go, that is, that the rods have to do ith the onditioning of olorless light sensations. Von Kries agrees ith Mrs. Franklin further in that the hanges in the ones ondition the olor sensations. Mrs. Franklin presents her theory (7) in an attempt to explain the defets of the other to theories and at the same time have a theory that onforms to the knon anatomy of the eye. Briefly, this theory onsiders the olor sensing a proess of evolution. In the earliest primitive retina olorless light only as pereived, as is still found in the peripheral portion of the retina. Colorless sensations are doe to deomposition of a hite-blak substane present both on the rods and omes, on the latter, hoever, in suh a differentiated ondition as to he apable of giv

13 ing rise to olor sensations. hite-blak and gray series. Rods an pereive only In the proess of development the moleules of the hite-blak substane on the ones beame differentiated, so that different parts of it responded to different ave lengths of light. This took plae supposedly in to stages, the first being that part responded to the longer ave lengths, giving rise to sensations of yello; the seond part responded to the shorter ave lengths, and gave rise to the sensation of blue. In the outer part of the periphery of the retina, at the outer part of the part ontaining both rods and ones, and of neessity ithin the part ontaining rods only, this differentiation still exists, and e seer hite, blak, blue and yello. It also existed, by this theory, in the fovea of the red-green blind individual. The seond stage of development is the differentiation takes plae in the part of the retina used mostly, that is in the maular region. Thus it is that the field for red and green is muh less than the field for yello and blue. Summed up, then, e find that in and around the fovea e have, in the normal retina, an area of unertain extent that pereives all the olors of the spetrum, hite and blak. Outside of this area there is another zone here blue, yello, hite and blak are pereived. Outside this zone is the third zone, extending nearly or quite to the ora serrata, in hih zone only hite and blak are sensed. In the maular region, here the yello

14 12 substane has differentiated into red and green, yello i s pereived by stimulation of the proper proportions of red-green moleules. If all three omponents are disassoiated e have our earliest sensation- gray. Of ourse in the portion of the retina here rods exist gray is seen by the dissoiation of the hite-blak substane of the rods as ell as by the ones. In the foveola, here only ones exist gray is seen only by total dissoiation of the photohemial substane in the ones. One point is important to remember, that the undifferentiated gray substane on the rods is very easily disassoiated, so that gray is seen by very slight stimulation; hile the more differentiated substane of the ones is more diffiultly dissoiated. Hene the gray of mixed olors requires greater digree of stimulation that the hite-blak gray. Aording to this theory the totally olor blind have an atavisti retina, the photohemial substane exists on rods and ones alike in the undifferentiated state. The olor blind of the ommon type, red-green, possess an undeveloped retina, the olor substane has stopped short of omplete differentiation, and exists on the ones in its first stage of development, that is into blue and yello. It must be admitted that the theory annot aount for the extremely rare ases of blue-yello olorblindness, ith red and green olor sensing pratially or quite normal.

15 13 Heredity in Color Blindness. The fat that olor blindness adheres fairly losely to ertain families has already been mentioned. Without going into detail regarding the theories of heredity involved it may be said that olor blindness is a ondition sex limited in ourrene and in its transmission. Pratiaally all olorblind persons are males, though some fe ases of female olor blindness exist. The hildren of olor blind fathers are rarely or never olorblind, be they sons or daughters. The hildren of the sons of the olorblind father axe not olorblind, but, the hildren of the daughters of a olorblind father are aording to the Mendelian la of heredity (8), affeted as follos: One-half of the sons ill be olorblind. This la holds provided the father of the daughters hildren is not olor blind. Should he be so, half of the daughters ill also be olor blind. No, if the olor blind daughter of suh a union h a s hildren all of the sons ill be likeise affeted. Aording to the Mendelian terminology olorblindness is a harateristi dominant in the male, and reessive in the female, pratially sex limited in its ourrene to the male, and also sex limited in its transmission by the female. This line of desent is shon by the folloing hart.

16 14 Expetation of Colorblindness in Offspring -Mendel. - Father and mother ithout fator ausing ondition - Female heterozygous for fator, not affeted, one-half sons affeted. - male heterozygous for fator. - Female homozygous for fator, affeted, all sons affeted. - Male homozygous for fator, affeted, all his sons affeted.

17 15 While the typial form of olorblindness is the red-green, it is seldom that the inability to sense red and green is equally defiient, There exists a more marked defiieny for either red or green, but both are defetive. There have been ases in hih the differene as so pronouned that the term red blind or green blind has been applied to the individual. If any of the present theories are orret, hoever, there an be no ase of pure red blindness or of pure green blindness. Careful tests have been devised by physiologists and psyhologists to determine just hat olors are not sensed, and to hat extent for eah olor the individual is defiient. The primary objet of the present study of this paper is to ork out the partiular type of olorblindness of a sophomore medial student, Mr. T., hose olorblindness as disovered in the ourse of routine examination in the department of Physiology of the College of Mediine. He had knon for a long time that his sensing of olors as different from that of his sister, and thought it different from that of other members of the family. Preliminary tests made by use of the Holmgren ools and by haying him pik out the books ith red bindings in the library of the Department tended to sho that he is pratially normal for reds and very defiient for greens. At the suggestion of Dotor MClintok and ith his kind assistane the study of the ase as undertaken. The riter ishes at this time to

18 l6 aknoledge his appreiation of the help and guidane of Dotor MClintok, and his gratitude to Dr. Mabel Williams of the Department of Psyhology of the University of Ioa, and to the Department of Physis of the University, for many ourtesies shon and assistane rendered. The tests made inluded pratially all the standard tests, together ith many of the finer tests of olor disrimination and onfusion, in so far as the neessary equipment as available. The results of these tests are given in tabular form, and if the subjet as asked to desribe a ertain phenomenon his exat desription is quoted. The tests used inlude Holmgren's ools, Nagel's olor onfusion ards, Hayes' (9 ) rings for testing olor thresholds, Lovibond's tinpmeter, spetrum, spetrosope, and perimeter. Test ith Holmgren ools. This test as made in the afternoon ith good light. A gray bakground as used. The tehni of the test as that laid don as standard: the mathing of ertain skeins given him. At no time as the name of any olor asked for or suggested. The result of this test is shon in the first exhibit. In eah ase the first piee is the one given him to be mathed. After the four standard olors had been mathed the observer said, "No if you'll let me pik out the greens for you I'll be glad to do so." The results of this seletion are shon as the last part of the first exhibit. When

19 17 asked, ho he seleted the olors he said that green to him as a "dead" olor, hile red as a "live" olor. This test as also arried out earlier ithout saving the olors seleted. For mathing the red standard he seleted light bron, yelloish red, reds, light gray, pink and yello. For the mathes to the yello standard he seleted yellos and light green. Mathing blue he seleted blues and greenish blue. To math the standard green he seleted grays and a fe greens.

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24 Nagel's olor onfusion tests. 18

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29 19 Part I. 1. Asked for the ards ontaining red spots, he seleted All, A8, A6. 2. Asked for the ards that ontained red spots only, he seleted A12, and said there as no other ard. 3.a) Asked for the ards ontaining green only, he seleted A9, A13, A15. b) Asked for the ards ontaining grey only, he seleted A15. ) Asked for the ards ontaining grey, he seleted A8, and said that it as rather a greenish grey. PartII. 4. Asked to name the olors in B1, he replied that they ere orange and red. 5.a) Asked to name the olors in B2, he alled dark bron, bron; alled reds reds; and did not kno light bron. b) Asked hat olors present on B3, he replied that they ere all green. ) Asked for the olors present on B4, he replied reds and brons. Supplementary A. 6.a) Asked for all the ards in set A ontaining red or reddish spots he seleted A6, All, and A12. 7.a) Asked to selet all the ards ontaining green, he said that all the ards ontained green. b) Asked for those ontaining green only, he seleted A4, A8, A14.

30 20 8. Asked to name the olors on B1, alled bron green, alled greenish red. Asked to name the olors on B2, named reds orretly, alled brons green. Hayes rotating diss for the determination of the olor threshold. These ere made in aordane ith the reommendation of Hayes, hite diss ith a radius of 95 mm. ere made. Upon these ere pasted irular rings of the four standard Hering olors, 5 mm. in idth, and at a distane of 60mm. from the enter, one strip on eah dis. On a fifth dis as plaed a strip of Hering's neutral grey, number 14, made the same as the olored irles. They ere slit and so plaed on the olor heel that any one ould be exposed at ill,and as large or as small an ar of the olor exposed as as desired. The experiment as arried on as follos: The observer Bat at a distane of one meter from the olor heel. Care as taken to have good light. * A sreen as loered in front of the olor mixer and a small setor of a olor exposed. It as set rotating, the sreen lifted, and the observer asked to name the olor. This as repeated for all the olors. At intervals the neutral grey as thron into onfuse the observer. At no time did the observer see the heel standing still ith any part of a irle exposed. The observer did not kno before tie experiment ho many olors ere on the olor heel. The results are given in tabular form, though

31 21 it must be noted that the olors dremaixed up at ill, at one time red, at another any olor hosen in no definite order. Red Green Blue Yello Deg. Named Deg. Named Deg. Named Deg. Named 125 Greenish 180 Orange or yello 4 Yello 180 Olive Green 180 Greenish 20 Pinkish 220 Greenish 195 Reddish 250 Greenish 220 Greenish 250 Greenish 230 Reddish Green or red Can not tell 255 Green or red 250 Greenish 270 Greenish 265 Red or green 285 Greenish 315 Red gray 360 Cannot tell, alls it 40Blue Hering's Neutral Gray #14. Deg. Named 105 Reddish 180 Reddish 195 Vermillion 280 Deep vermillion 350 Gray, Has lost its vermillion Some of the observer's omments on the above exposures are of interest. he alled it greenish. On exposing 220 degrees of red Immediately folloing this 220 degrees of green ere exposed. He alled this greenish also, saying that it as like the preeding one

32 22 only less intense. Reduing the amount of green to 195 he alled it reddish, "slightly more so than the one preeding". Exposing 180 degrees of red he alled it greenish, or olive green. Immediately hanging to green 180 he said that this as greenish but less so than the one just preeding. During the test he repeatedly said that if he ould only get loser to the heel he thought he ould tell the olors better. Privilege as given, though the results ere not reorded, but seemed to make no differene. It is interesting to ompare the threshold of this observer ith those of the protanope, to deuteranopes, and an average test of forty omen ho made no mistakes ith the Nagel test, reported by Hayes (10). In the folloing figures an X indiates that the observer ould not name the olor although the full irle ere exposed. Observer Red Green Blue Yello Mr. T. 315 X 4 4 Miss G.S.Protanope X Miss M.S. Beuter 110 X Miss I.B. Deuter Average of forty Normals Although the blue and yello thresholds of our ase seem very lo, repeated tests on the one day failed to ause any mistakes at this limit. On another day he did, hoever, require a setor or 37 degrees to reognise the blue.

33 23 This one test is suffiient to sho that although his sensation of green is muh more defiient than that for red, yet he is red-green blind. Testing for olor threshold ith the Lovibond's tintometer. In this experiment standard olor glasses of varying intensity or depth of olor beginning ith the non- determinable and running up to the deep olor, from.1 up to 20.0, the depth of olor being those of Lovibond s instrument, are used. The observer looks through to small openings plaed about 16 inhes from the eyes, so that he uses binoular vision for both openings. A small amount of olor is plaed in one opening, the other is simply hite glass. The observer is no direted to look and to tell hat he sees, if there is any differene and if so here. The olored glasses are first on one side, then on the other, in no definite order. Oasionally a plain hite ontrol is slipped in. The amount of the olor is sloly inreased until he gets it right a suffiient number of times out of ten; this is his olor threshold. In the table the sign is orret and is rong. Amount of Color Blue ?

34 24 His threshold for blue may therefore be onsidered as about.8 Normal, average of 5,-.839 Amount of Color Yello His threshold for yello may therefore be taken as beteen.3 and.4 Normal, average of 5,-.476 Amount of Color Red His threshold for red may be taken as beteen 2.00 and 2.50 Normal, average of 4,-.452 Green Green is made by using blue and yello in superposition. Initial shos the olor alled, other symbols are the same. 1y 1b 1y 5h 6y 6b 10y 10b 1 5y 15h 20y 20b 30y 30b y y y y b y y y? y y y y? y y y y?? y?? From this it is seen that his sensing of green in any degree of intensity of amount is extremely doubtful. His green olor sense is pratially nil.

35 25 Desription of the spetrum. A spetrum about sixteen inhes in length as thron by an ar light upon a hite surfae, and the observer asked to desribe it. Beginning at the red end he stated that he sa red to a ertain point, as far as normal observers see it. The red extended to about one half of the red portion, hen he said there as a trifle of orange, and then a broad band of yello extending nearly to the blue. Then there as a band of gray, about to inhes in idth beteen the yello and blue. Blue as seen in a broad band, the band reahing through the purple as far as the normal observer present sa it or farther. This onfirms the spetrosopi tests given later in respet to the extent of his spetrum. The gray band as desribed ithout any suggestion on the part of those present. Spetrosope. The spetrosope as illuminated by an ar light. Ten readings ere made at eah end of the spetrum, the observer alternating ith another reader so as to avoid any fatigue. Sine departures from an average are important the entire number of readings is given. Readings are given in ave lengths, mumu. Violet end: 400, , 388, 399, 387, 383, 391, 396, 386, Av Red End: 679, 674, 688, 680, 673, 668, 684, 675, 674, 688. Av

36 26 The limitations of the spetrum as determined by observations on three supposedly normal individuals (11) are as follos: Observer Red end Violet end Mr. K. 701±8 411±4 Dr. S. 693±5 428±4 Mr. S. 682±8 430±4 Mr. T (Observer) Normal (Calkins) From this table it ill be seen that the observer s spetrum is not shortened, and he is aording to Whipple s lassifiation as given earlier (12), a deuteranope. Perimeter. The observer'3 fields ere taken ith the Hardy perimeter. Ne standard olors ere inserted into the dis just before starting to take the fields. are attahed on the usual perimeter hart. The fields For hite, blue and yello the fields are normal, and no errors ere made that ere in any ay unusual or abnormal. The red fi field in eah eye as onstrited, more in the left than in the right. The green field is not shon beause the observer as never sure of the olor, in fat the name green as not mentioned by the observer at any time during the taking of the fields. His notation of the olors red and green are given in detail in the four quadrants,

37

38 27 Right Eye 90-0 Temporal nasal Angle Color shon Called by observer 90 Green Yello at 40,reddish pink at 20 Red White at 50, blue at 40, green at 25, red at 10 0 (tem ) Green Yello at 60, pink at 30, reddish at enter. Red Yello at 60, pink at Green Yello at 50, red at 25. Red Red at (nas) Green Yello at 40, red at 25 Red White at 50, yello at 40, red at 20. Left Eye Nasal Temperal Angle Color Shon Called by observer 90 Green Yelloish at 40, pink at Red 25. White at 35, Yelloish red at 25, red at (Nas) Green White at 40, pink at 20, red at 10. Red Yello at 45, pink at 30, red at Green White at 60, yello at 50, red at 20. Red Yello at 55, pink at 28, reddish at (Tem ) Green White at 60, pink at 35, red at 20. Red Yello at 45, pink at 35, red at 20. To the riter the above is very interesting in the ay it suggests the possible development of the yello substane into red-green. Without exeption the sequene of hange from the periphery inard as from the hite, into yello, into pink or red. In taking a large number of perimetri harts on normal

39 28 eyes the riter has observed the marked onstany ith hih red is first alled yello as it is brought in from the periphery. This ompletes the experiments or tests made upon the observer, Mr. T. One other investigation as arried out that is interesting. Holmgren ools ere sent to the family of Mr. T., and to brothers and the father ere tested by use of the ools. The seletions made by these are attahed to the exhibit ard. It is very interesting to note that the same type of seletion of olors obtains in all three brothers. The father is apparently normal, hih makes the line of transmission through the mother, in aordane ith the usual line of transmission aording to the Mendelian la. From our study of the ase e arrive at the folloing onlusions: 1L. The ase studied is a deuteranope, that is, his spetrum is not shortened. 2. He is a red-green blind individual, although he is manifestly more defiient in his sensing of green than he is of red. 3. The differene in his sensing of red and green is most likely due to a sensing of the differene of intensities, for as he said in desribing them, "Red is a live olor, hile green is a dead one". On another oasion he piked up a skein of standard red ool and said,-, "That olor hatever it may be, is a stimulating olor. It typifies my idea of energy. Where I got

40 29 it I do not kno, but that is the ay it seems!" 4. In his heredity he follos fairly losely the Mendelian la of heredity for olor blindness. The rough test that as made of the rest of the family ould indiate that not only is the olor blindness transmitted to the three brothers from the maternal grandparent(?)but that the partiular sensing of red better than green as also part of the transmission, sine all three brothers are alike in so far as the one rough test of the Holmgren ools ould sho.

41 30 Bibliography 1. Fritsh in, Anatomy and Histology of the Eyeball. Selzmann. Transl. by E. V. L. Bron. 2. Hoell, Text book of Physiology, Fifth Edition, p Baird, Problem of Color Blindness, Psyhologial Bulletin v, Hoell, Textbook of Physiology, fifth Ed. p Ibid, p Calkins, Introdution to Psyhology, p Mind, Vol. 2. p Mendel's Priniples of Heredity. 9. Hayes, Color Sensations of the Partially Color Blind. Amer. Jour. Psyhol. July, Ibid. 11. Dotor Williams, Dept. Psyhology, University of Ioa. 12. Whipple, Manual of Mental and Physial Tests. Other referenes read in preparation of ork: Jennings, Color Vision and Color Blindness Hill (Editor), Further Advanes in Psyhology. Edridge-Green, Colour Blindness. Abney, Reent Researhes in the Problem of Color vision.