BEFORE beginning a discussion of

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1 Lethal Internal Temperatures for the Chicken, from Fertile Egg to Mature Bird ROBERT E. MORENG AND C. S. SHAFFNER Department of Poultry Husbandry, University of Maryland, College Park BEFORE beginning a discussion of lethal body temperatures, it must be pointed out that there can be no sharply denned high or low body temperature that always results in death. Whether or not a certain body temperature kills the individual depends upon such factors as length of exposure to a given temperature, rate of cooling or warming, individual resistance, etc. In the experiments to be described, unusually high and low ambient air temperatures were used to eliminate as far as possible the effects of time as a factor. The potentiometer available for this study recorded temperatures in degrees Fahrenheit; to facilitate comparison, the centigrade temperatures reported by other authors have all been converted to Fahrenheit and stated to the nearest degree. There have been many reports on the effects of various environmental temperatures on the viability of the embryo, but unfortunately most authors failed to record the actual internal temperature of the egg. Colasanti (875) immersed eggs in an ice bath of 4 to 5 F. for one to two hours. He observed that even though the content of the egg was found to be a solid mass, the vitality of the germ was Scientific paper No. A9. Contribution No. 39 of the Maryland Agricultural Experiment Station (Department of Poultry Husbandry). Present address: Poultry Department, North Dakota Agricultural College, Fargo, N. D. (Received for publication August, 0) 55 not injured. It was concluded that the dormant germ is less sensitive to temperature shock than the developing embryo. Eggs which were exposed to an ice-salt mixture at 0.4 F. for a half hour were reported by Rabaud (899) to result in abnormal embryos; and Grodzinski (933, 934) found that eggs exposed to a temperature of 7 F. for four days previous to incubation developed germinal discs which lacked embryos or blood vessels. Observations on the hatching power of eggs after exposure to various low environmental temperatures were made by Elford (9), Mauro (93), Mussehl and Bancroft (94-), Scott (933), Phillips (945), Funk (947), and Olsen and Haynes (948). In general these workers observed little or no decrease in hatchability following short-term exposure to relatively low environmental temperatures. Moran () reported that when the internal temperature of the egg cooled to below 3 F. fertility was quickly lost and concluded that the germination power is probably destroyed immediately at internal temperatures of approximately 9 to F. Jull, McCartney and El- Ibiary (948) reported that subjecting chicken hatching eggs in cases to F. for as long as 0 hours did not seriously impair hatchability. This treatment caused the internal temperature of the egg to reach approximately F. The ability of the embryo to withstand Downloaded from at Penn State University (Paterno Lib) on September 8, 0

2 5 ROBERT E. MORENG AND C. S. SHAFFNER changes in temperature during the incubation period was studied by Lamson and Kirkpatrick (98). They found that during the first 4 hours of incubation embryos were able to stand four to five hours exposure to a temperature of 50 F. After the first 4 hours of incubation, the time could be increased up to 5 hours; after the seventeenth day, exposure for more than six hours caused death of the embryo before hatching time. Eggs which had been incubated from 9 to 4 hours were found by Grodzinski (934) to have a considerable number of dead and defective embryos as a result of having been subjected to 7 F. for to 0 hours. Kaufman (934) reported normal hatches from eggs that had been exposed at various stages of incubation to a temperature of 54 F. for 4 hours. Romanoff (939) noted that the susceptibility of the embryo, as shown by total mortality, was greatest from the exposure to high temperatures during the early periods and greatest from the exposure to low temperatures during the later periods of incubation. Randall (943) observed that in the chick shivering ceases when the body temperature reaches approximately 8 F. and breathing stops at 59 F. By suspending birds in a water bath at 43 to 53 F., Sturkie (94) studied the tolerance of the adult chicken to hypothermia. The lethal internal body temperature of hens ranged from 73 to 75 F., while that of males ranged from 7 to 7 F. Yeates, Lee and Hines (94) and Lee, Robinson, Yeates and Scott (945) described the physical reactions of the hen when its body temperature was raised to 3 F. Observations on one chicken by Randall and Hiestand (939) showed that when the bird's body temperature was raised to 7 F. and maintained for a brief period of time the bird died. In most of the previous works, the authors have not recorded the lethal temperatures when the factor of time of exposure is kept at a minimum. This investigation was made to determine the lethal internal temperatures of the embryo of the unincubated egg, of the embryo during development, and of the chicken from day of hatch to maturity. It was felt that a continuous study of this type would also supply valuable data in determining the point of development at which the chicken changes from a partially poikilothermic animal to a true homiothermic animal. MATERIALS AND PROCEDURE The experiment consisted of a series of studies on approximately 3,000 eggs in various stages of incubation and over 90 chickens ranging in age from day of hatch to maturity. The eggs used were from New Hampshire hens and were selected for uniformity of size and shape, weighed 4 to 5 oz. per dozen, and were never held for more than seven days before being incubated. The New Hampshire chickens used throughout this study were battery grown stock fed the Maryland Experiment Station broiler mash and were selected as being normal representatives of their particular age group. Temperatures of the birds and eggs were measured by means of copperconstantan thermocouples, which were attached to a recording potentiometer. A special terminal switch box connected with the potentiometer made it possible to record temperatures from different thermocouples by merely switching from one to the other. The lethal temperature was considered to be that which killed approximately 50 percent of the exposed individuals. The study of low lethal temperature for the developing embryo was carried out by exposing the eggs to an environmental Downloaded from at Penn State University (Paterno Lib) on September 8, 0

3 LETHAL TEMPERATURES FOR EMBRYOS AND CHICKENS 57 temperature of 0 F. Data were collected on eggs from zero to 0 days of incubation. Thirty eggs were used for each trial. Six of these eggs had thermocouples inserted through a small hole bored in the large end of the egg, so that the point at which the temperature was measured was at the center. These eggs were used only for recording temperature, since the insertion of the thermocouple caused physical damage to the egg. It was felt that their average temperature represented the average temperature of the remaining 4 eggs. On the basis of preliminary trials, exposures were selected which were intended to bracket the lethal point. Six eggs were removed after various intervals of exposure. These eggs were then incubated at normal temperatures and later broken out in petri dishes and the number of dead and live embryos recorded. Eggs which had been treated at zero, one, and two days of incubation were held and broken out on the third day, since heart beat in the live embryo could be clearly seen at this time. All other eggs were opened 4 hours later. Time played an important role in the determination of the lethal temperature, since the temperature of the eggs remained relatively constant for a period of about 55 minutes when the eggs were in the process of freezing. To determine the high lethal internal egg temperatures, the eggs were placed in an oven with an air temperature of 0 F. To insure a uniform and rapid rate of warming, the air in the oven was circulated with a small electric fan. The same procedure described above was used to determine whether or not the treatment had killed the embryo. As the internal temperatures of the eggs increased, groups of eggs were removed at intervals of four degrees. After the lethal temperature for the incubating eggs had been determined, a series of trials was conducted to determine how long eggs in various stages of incubation could withstand internal temperatures of 0 F. This was done by raising the temperature of the eggs to 0 F. in the oven having an ambient temperature of 0 F. and then maintaining the temperature of the eggs in a second oven set at 0 F. Lots of thirty eggs* each were so treated at 0, 4, 7, 9, 3, 4, 5, 8, 9, and 0 days of incubation. At various periods of time, four to six eggs were removed and broken out. Lethal body temperatures for chickens from day of hatch to maturity were determined by exposing the birds to an ambient temperature of 0 F. Chicks were placed in wire cages so that each chick was contained in a separate compartment to prevent huddling and thus ensure uniform exposure. Twenty-four chicks of the same age were used in each test, and the body temperatures of half of these chicks were recorded. The thermocouples were inserted to a depth of one inch into the body cavity by passing them through the naval of the young birds. This proved to be an easy source of entry to the body cavity and could be re-opened by puncturing with a pair of forceps. In older birds, entry was obtained by surgical methods and the incision closed with metal wound clips. Thermocouples were usually inserted in young birds after the exposure had caused the birds to become inactive, thus making it easier to keep the thermocouples in place. Individual thermocouples were checked frequently to assure that the movements of the bird had not worked a thermocouple out from the desired depth in the body cavity. The body temperature of each individual was checked periodically and when the average body temperature for the group reached the range which preliminary tests had indicated to be lethal the birds were removed and put in a forced- Downloaded from at Penn State University (Paterno Lib) on September 8, 0

4 58 ROBERT E. MORENG AND C. S. SHAFFNER draft incubator at 99 F. to recover. After approximately one hour of warming, the birds were removed and checked for signs of life. Their sex and body weight were recorded. In this phase of the work, likewise, the lethal temperature was considered to be that temperature which would kill 50 percent of the individuals. To check the results of the previous study, a second technique was employed to determine the temperature at death. One man was stationed in the deep freezer with a speaking tube to the second man posted outside at the potentiometer. When a bird died, the operator on the outside recorded time and body temperature. A definite muscle spasm accompanied by a few deep gasps for breath were usually clear indications of death. The lethal temperature recorded by this method was in most cases a few degrees below that which resulted in a 50 percent mortality as previously described. To verify that lethal temperature had been reached, a number of these birds were removed and re-warmed. Records of low lethal body temperature were made on chicks daily from day of hatch (denoted as 0 days) to days of age. After this three-week period, recordings were made on various birds at different ages as follows: 4, 5,, 0,, and weeks of age, and on mature hens. It was found necessary to clip a large portion of the body feathers on the older chickens and mature hens to increase their rate of heat loss, since their heavy insulation of feathers enabled them to withstand the cold environment for a number of days without any appreciable change in body temperature. High lethal temperature for the chicken was studied by placing a chicken in a wire cage and placing this cage in an oven at 0 F. Only one bird was exposed at a time and the internal body temperature was recorded by inserting a thermocouple into the body cavity by the same means described previously. Length of exposure and temperature at death were recorded in all cases. Data were obtained on six birds in each of the following age groups: day of hatch, 3,, 9,, 5, 8 days of age; 4 and 8 weeks of age, and on two hens at maturity. RESULTS AND DISCUSSION A Low Lethal Internal Egg Temperatures for the Embryo A record of the internal temperature of an egg exposed to 0 F. may be seen in Figure. This continuous recording made with the recording potentiometer provides an interesting picture of the eggs' temperature during the process of freezing. As can be seen from the chart, the eggs cooled very rapidly, reaching the freezing point in about 55 minutes. It is thus apparent that the embryos were actually exposed to a temperature between 9 and F. for roughly two-fifths of the total exposure time or about to 40 minutes. In some cases, as shown on the chart, the temperature dropped below the freezing point to F. This was probably due to the phenomenon of supercooling. The supercooled state existed for only a short time before the temperature returned to 9 F., where it remained for about 5 minutes during the process of freezing. It may be seen from Figure that after the egg had frozen the temperature curve once more commenced to fall. This part of the curve represents the cooling of an egg in the solid state. The low lethal temperature for the developing embryo from zero days of incubation to 0 days of incubation is recorded in Table. As stated previously, time was found to be an important factor in determining the low lethal temperature, since the temperature of the egg remained Downloaded from at Penn State University (Paterno Lib) on September 8, 0

5 LETHAL TEMPERATURES FOR EMBRYOS AND CHICKENS 59 relatively constant during the process of freezing. Eggs which had been exposed to low temperatures at zero days of incubation showed signs of early embryonic death when opened on the third day of incubation. Evidence of the development of the germinal disc was noted at this early part of the incubation period, since at this time the lethal temperature was 9 F. and the total exposure time minutes. Figure presents the exposure time graphed by days during the period of development. It can be seen that there is 0 00 FIG.. Continuous record of internal temperature of an egg exposed to an air temperature of 0 F. Supercooling is demonstrated by the break in the line when the temperature reached F. time. It may be seen from the data in Table that the lethal temperature varied from 9 to F. with exposure time ranging from 70 to minutes throughout the study. Indications are that the embryo is less resistant to cold temperatures from the eighth to the fourteenth day of incubation, since during this period the exposure needed to cause 50 percent mortality decreased from minutes to 70 minutes. A slight rise in exposure time can be noted from the fifteenth to the eighteenth day. The developing embryo appeared to be most resistant during the a very pronounced decrease on the fifth day in the time which the embryo can withstand the low temperatures. There was a difference of twenty minutes in lethal exposure time between the sixth and the eighth days. After this period, the time remains constant until the previously mentioned rise near the end of the embryonic period. The chronological change in the ability of the embryo to withstand low temperatures as shown in this study is of value in determining the time the chicken embryo changes in its behavior from that of a Downloaded from at Penn State University (Paterno Lib) on September 8, 0

6 0 ROBERT E. MORENG AND C. S. SHAFFNER TABLE. Average low lethal internal egg temperature for the developing embryo, zero to twenty days of incubation Days of Av. lethal A v. exposure time incuba- internal,.,. tion temperature _IO F* F No. of trials** ' * Average exposure time necessary to kill 50 percent of the embryos. ** Thirty eggs were'used in each trial. cold-blooded animal. Pembrey, Gordon and Warren (894-8) suggested that this change takes place at hatching time, while Romanoff (939) presented data which indicate that the change takes place after the tenth day of incubation. The data reported in this paper agree in part with both hypotheses. The fact that between the sixth and eighth days of incubation there is an abrupt change in the length of time that the embryo can withstand exposure to low temperatures indicates that the embryo undergoes a definite change in its development at this time. The fact that the embryo will withstand a much lower temperature than the chick, suggests that another very definite change takes place at hatching time. It is felt that the changes which take place at hatching time are probably the greatest that the embryo undergoes, and show that there has been a positive shift toward the homoiothermic condition. B High Lethal Internal Egg Temperatures for the Embryo The lethal temperature for the embryo ranged from 9 F. prior to incubation to about 08 F. on the fourth and fifth days of incubation (Figure 3). An interesting change in lethal temperatures may be noted at two points of the graph. The first change came after one day of incubation, at which time the embryo became very susceptible to high temperature. Between the fifth and sixth days of incubation, the lethal temperature rose seven degrees from 07 to 4 F. This seems to indicate that a drastic change has taken place in the development of the embryo which increases its resistance to heat. During the remainder of the period of development, the lethal temperatures ranged fromll4 toll8 F. The lengths of time which the embryo could withstand high temperatures was studied to further substantiate the differences found in the high lethal temperatures associated with various stages of embryonic development. Eggs were heated rapidly to an internal temperature of 0 F. and then held at this temperature. The data on exposure time as recorded in hours can be seen in Table. The pattern followed by these data is similar to that shown by the data on high temperatures as graphed in Figure 3. At zero days of incubation, a period of two hours at 0 F. was required to kill 50 percent of the embryos. On the fourth day of incubation,, this time had decreased to ten minutes and on the seventh day and thereafter the time was about eight hours. When the internal temperature was maintained at 0 F. on the fourth day of incubation, the lethal exposure time increased to hours. This demonstrates Downloaded from at Penn State University (Paterno Lib) on September 8, 0

7 LETHAL TEMPERATURES FOR EMBRYOS AND CHICKENS en 90 * I I S <K v> o a x t I z <r X < U- </> O O J : l I I l l l l 8 0 DAYS OF INCUBATION «4 8 0 FIG.. Average lethal exposure time for the developing embryo, zero to twenty days of incubation, to 0 F. Each dot represents data collected from eggs. 9. %» «Downloaded from at Penn State University (Paterno Lib) on September 8, DAYS OF INCUBATION FIG. 3. High lethal internal egg temperatures for the developing embryo, zero to twenty days of incubation. Each point represents the data obtained from eggs.

8 ROBERT E. MORENG AND C. S. SHAFFNER TABLE. Lethal exposure time for th embryo when the internal egg temperature was maintained at 0"F. Days of incubation Lethal exposure time (minutes) * Thirty eggs were used for each trial. No. of trials* that a difference of four degrees apparently marks a critical point in the lethal temperature of the embryo. This critical point may be a direct result of a sudden increase in metabolic rate observed on the third day of development (Noyons and Pascal de Hesselle, 939). C Low Lethal Body Temperatures for the Chicken The data concerning the low lethal body temperatures for chickens from day of hatch to days of age are shown in x < CO LLi <s> Q 70 ing Figure 4. During the first 0 days of age, there was a steady rise in lethal body temperature. This period of growth is the most interesting to observe, since in the first 0 days the bird apparently passes through a stage of development in which its lower lethal temperature rises seven degrees. After this period, the lethal temperature remains more or less constant. The data concerning the full range from day of hatch to maturity are shown in Figure 5. It will be seen that following the very rapid initial rise in temperature (zero to two weeks) there is a slow rise extending through the growth period to weeks of age. During this period, the lethal temperature increased approximately five degrees. The lethal temperature for the mature hen as observed on only three hens was approximately 73 F., or an increase of about four degrees above that found for the sixteen-week-old birds. This latter figure is in agreement with that reported by Sturkie (94). This change was followed by an increase of one to four degrees in the period from weeks of age to the mature hen. The rapid rise in accompanying exposure time can be seen in Figure. Downloaded from at Penn State University (Paterno Lib) on September 8, 0 FIG. 4. Low lethal body temperature for the chick, from day of hatch to twenty-one days of age. Each point represents data collected on chicks.

9 LETHAL TEMPERATURES EOR EMBRYOS AND CHICKENS 3 The lethal temperatures determined for the chicken are remarkably close to those reported for the eastern house wren by Baldwin and Kendeigh (93). The low lethal body temperature for the young house wren was 47 F. As the wren matured, the change in lethal temperatures this stage is beginning to function as a completely coordinated unit, with a more complete development of the thermoregulatory mechanism. The fact that the thermoregulatory device of the chick is not completely developed at hatching time is probably beneficial to the bird X z K X < «> a 8 0 WEEKS OF AGE FIG. 5. Low lethal body temperature for chickens, day of hatch to the mature hen. Each dot represents data collected on birds; each cross, data from individual birds. closely resembled that reported here for the chicken. These workers reported that the lowest internal temperature that the adult eastern house wren could withstand was 74. F. The rapid rise in low lethal temperature the first ten days after hatching coincides with the rise in body temperature during the same period (Lamoreux and Hutt, 939; and Randall, 943). About this time (5 days of age) there is a peak in the basal energy metabolism (Barott, Fritz, Pringle and Titus, 938). These facts indicate that the chicken at Mature Hen since it allows the chick to be more resistant to temperature shock. D High Lethal Body Temperature for the Chicken When the chicken was exposed to an ambient temperature of 0 F., it quickly lost its ability to regulate body temperature. The temperature of the body cavity rose rapidly in young chicks soon after the birds were subjected to the high temperature. Older birds maintained their body temperature somewhat better than the chick but only for a short period. Downloaded from at Penn State University (Paterno Lib) on September 8, 0

10 4 ROBERT E. MORENG AND C. S. SHAFFNER V) - Z 5 z or (0 O CL X DAYS OF AGE FIG.. Average lethal exposure time for chicks, day of hatch to twenty days of age, at 0 F. Each dot represents data collected on 4 chicks. Table 3 summarizes the results obtained on the study of high lethal body tempera- TABLE 3. High lethal body temperature for chickens from day of hatch to maturity Age Day of hatch 3 days of age days of age 9 days of age days of age IS days of age 8 days of age 4 weeks of age 8 weeks of age Mature hen Av. body temperature at death F Av. exposure time (min.) to 0 F No. of birds involved tures. Average body temperature at death was remarkably uniform for all age groups studied. Individuals, regardless of age, varied only from to 7 F. Baldwin and Kendeigh (93) reported the high lethal body temperature for the adult eastern house wren, regardless of age, to be approximately F. A general trend toward an increase in average exposure time is the only difference which could be noticed between the age groups. Up to four weeks of age, the chickens could withstand exposure' to 0 F. for only 0 to 3 minutes; after this time, they were able to withstand exposure for increasing lengths of time. This resistance Downloaded from at Penn State University (Paterno Lib) on September 8, 0

11 LETHAL TEMPERATURES FOR EMBRYOS AND CHICKENS 5 to high temperatures is brought about by the further development of the thermoregulatory mechanism. An increase in panting rate accompanied the increase in body temperature. At a point a few degrees below that at which the bird died, the very rapid panting rate decreased sharply and then ceased as the bird quickly lost its ability to function as an organized body. Death was accompanied by a brief muscle spasm, which in all cases made the determination of this point quite distinct. SUMMARY. Studies were made to determine what high and low extremes in internal egg temperatures the embryo in various stages of incubation could withstand. Data were collected on over 3,000 eggs from zero to twenty days of incubation. The high and low lethal internal body temperatures of approximately 90 chickens of various ages were studied, and average temperatures at which most birds died were determined. Temperatures in the body cavity of the chicken and at the center of the egg were measured by the use of copper-constantan thermocouples connected to a recording potentiometer. In order to eliminate as many factors as possible, especially time, extremes in ambient air temperatures were used. Low temperature exposure was 0 F. ( 3. C), while high temperature exposure was 0 F. (7. C).. When eggs were removed from the incubator and exposed to 0 F. for about 55 minutes, their internal temperature reached about 9 F. At this point the egg commenced to freeze and the internal temperature remained constant for about 5 minutes, after which it approached the temperature of the environment. Supercooling of the egg at 0 F. was demonstrated, as the internal temperature was lowered to F. for a short period of time, after which it returned to 9 F. Total lethal exposure time to 0 F. was approximately minutes, only about 40 minutes of which the eggs' internal temperature was as low as 9 to F. High lethal internal egg temperature for the embryo ranged from an average of 0 to 9 F., increasing, in general, as the embryo development progressed. 3. The average low lethal body temperature for chickens was found to be 0 F. on day of hatch and progressively increased to 7 F. for mature birds. The high lethal body temperature ranged from an average of to 7 F. for all age groups. 4. The data collected indicate that a change in the poikilothermic characteristics of the embryo takes place about the seventh day of incubation. At this point the lower limit of time considered lethal to the embryo decreases, while the high lethal internal egg temperature for the embryo rises. A definite change is also indicated at hatching time when the chick's low lethal temperature rose from an average of 9 F. (80 minutes exposure to - 0 F.) to 0 F. ( minutes exposure to -0 F.). REFERENCES Baldwin, S. P., and S. C. Kendeigh, 93. Physiology of temperature of birds. Sci. Pub. Cleveland Mus. Nat. Hist. 3: pp. 9. Barott, H. C, J. C. Fritz, E. H. Pringle and H. W. Titus, 938. Heat production and gaseous metabolism of young male chickens. J. Nutrition 5: Colasanti, G., 875. liber den EinflussderKalteauf die Entwicklungefahigheit des Hiihnereies. Arch, f. anat. Physiol, u. wissensch. Med. 875: Elford, F. C, 9. Can. Exp. Farms Int. Rept. of the Dominion Poul. Husbandman. Funk, E. M., 947. Factors influencing hatchability in the domestic fowl. Missouri Agri. Exp. Sta. Bui. 34. Grodzinski, Z Uber die Entwicklung von Downloaded from at Penn State University (Paterno Lib) on September 8, 0

12 NEWS AND NOTES unterkiihlten Huhnereiern. Archiv. fur Entwicklungsmechanik. 9: Grodzinski, Z., 934. Weitere Untersuchungen ttber den Einfluss der Unterkuhlung auf die Entwicklung der Huhnereier. Archiv. fiir Entwicklungsmech. 3:53-7. Jull, M. A., M. G. McCartney and H. M. El-Ibiary, 948. Hatchability of chicken and turkey eggs held in freezing temperatures. Poultry Sci. 7: Kaufman, L., 934. Uber den Einfluss von Temperaturen unter dem Entwicklungaminimum auf bebrutet Huhnereier. Roux' Arch. Entwicklungsmech. 3: Lamson, G. M., Jr., and W. F. Kirkpatrick, 98. Factors in incubation. Storrs Agr. Exp. Sta. Bui.. Lamoreux, W. F., and F. B. Hutt, 939. Variability of body temperature in the normal chick. Poultry Sci. 8: Lee, D. H. E., K. W. Robinson, N. T. M. Yeates and H. I. R. Scott, 945. Poultry husbandry in hot climates Experimental enquiries. Poultry Sci. 4: -07. Mauro, F., 9. II trattamento frigorifico delle uova (di Gallina) e le sua influenza sulla capacita di sviluppo della macula germinativa. Atti della Societa Italina di Scienze Naturali e del Musco Civico di storia Naturale in Milano :39-4. Moran, T.,. The effect of low temperature on hens' eggs. Proc. Roy. Soc. Lond. 983: Mussehl, F. E., and P. Bancroft, 94-. Effect of low temperatures on hatching power of hens' eggs. Poultry Sci. 4: Noyons, A. K. M., and P. M. H. Pascal de Hesselle, Research assistant appointments on projects of the Ohio State University for 0-5 are: O. J. Cotterill (M.S., 948, Ohio) and Gordon Strite (B.S., 938, Cornell) in processing and product preservation; R. H. MacDonald (M.S., 0, Ohio) in poultry marketing; N. J. Beck (B.S., 0, Kansas); T. H. Coleman (M.S., 948, Alabama) and E. F. Godfrey (M.S., News and Notes {Continued from page 48) 939. Uber den Stoffwechsel des Hiihnereies und die BedeutungderLuftkammer. Acta BreviaNeerlandica de Physiologia, Pharmacologia, Microbiologia, e.a. 9: Olsen, M. W., and S. K. Haynes, 948. The effect of different holding temperatures on the hatchability of hens' eggs. Poultry Sci. 7: Pembrey, M. S., M. H. Gordon and R. Warren, On the response of the chick, before and after hatching, to changes of external temperature. J. Physiol. 7: Phillips, R. E., 945. Hatchability as influenced by environmental and different storage temperatures. Poultry Sci. 4: 5-8. Rabaud, E., 899. De I'influence de la congelation sur le developpement de l'oeuf de poule. C. r. Acad. Sci. 8: Randall, W. C., 943. Factors influencing the temperature regulation of birds. Am. J. Physiol. 39: 5-3. Randall, W. C, and W. A. Hiestand, 939. Panting and temperature regulation in the chicken. Am. J. Physiol. 7: Romanoff, A. L., 939. Effect of temperature shock on development of the chick embryo. Proc. Seventh World's Poultry Cong., Cleveland, Scott, H. M., 933. The effect of age and holding temperatures on hatchability of turkey and chicken eggs. Poultry Sci. : Sturkie, P. D., 94. Tolerance of adult chickens to hypothermia. Am. J. Physiol. 47: Yeates, N. T. M., D. H. E. Lee and H. J. G. Hines, 94. Reactions of domestic fowls to hot atmospheres. Proc. Roy. Soc. Queensland. 53: , Ohio) in poultry genetics and physiology. VIRGINIA NOTES At the 5th anniversary meeting of the Virginia State Poultry Federation, held at Blacksburg, awards for outstanding contributions to the improvement of the poultry industry were presented to H. L. Moore, Head of the Poultry Department, and to A. L. Dean, Associate Poultry Downloaded from at Penn State University (Paterno Lib) on September 8, 0 {Continued on page 79)