614 



DR SUTHERLAND SIMPSON ON 



Table IV. 



Mean Temperatures from three Observatiovis made at the same liours (7 a.m., 7 p.m., 

 and midnight in the case of A and B ; 9 a.m., noon, and 6 p.m. in the case 

 of A', A", B', and B") in Hens A, A', A" {Incubating) and B, B', B" (Controls), 

 during the -whole period of incubation and, five days after hatching. 



Hen. 



1 



2 3 



4 



5 



6 



7 8 



9 



10 



11 



12 





°C. 

 A 41-07 

 B j 41-23 



°C. 



C. ° C, 

 40-73 ! 40-57 

 40-93 41-30 



°U, 1 °c. 

 40-7 1 40-6 

 40-73 40-80 



40-53 

 41-13 



"0. 

 40-9 

 41-03 



°C. 



40-47 

 40-87 



°C. 

 40-73 

 41-10 



"0. 



40-7 

 41-23 



" U. 

 40-63 

 40-70 





A' 

 B' 



40-73 40-83 

 41-47 41-60 





40-63 

 41-07 



40-87 

 41-47 



41-0 



41-97 



41-40 

 41-93 



41-27 

 41-53 



41-17 

 42-03 



41-43 

 41-47 



41-20 

 41-57 





A" 

 B" 



40-93 

 41-93 



40-93 

 42-00 



41-10 



42-07 



40-97 

 41-67 



40-60 

 41-93 



40-87 

 42-30 



40-87 

 41-70 



... 



41-20 

 41-87 



40-97 

 41-90 



41-17 



41-60 







Hen. 



13 



14 



15 



16 



17 



18 



19 



20 



21 



22 



23 



24 



25 



A 

 B 



° C. 



40-67 

 40-67 



°C. 

 40-73 

 41-37 



°C. 

 40-70 

 40-93 



C. 



°C. 

 40-70 

 40-80 



°C. 

 40-90 

 40-63 



°C. 



40-63 

 40-83 



°C. 



41-13 

 40-63 



°C. 

 41-40 

 40-77 



°C. 

 41-50 

 40-93 



°C. 

 41-53 

 40-87 



°C. 



41-17 

 41-10 



°C. 



41-00 

 41-03 



A' 

 B' 





41-23 

 41-90 



41-20 

 41-83 



41-00 

 41-63 





41-17 



41-80 



41-40 

 41-47 



41-50 

 41-80 



41-31 

 41-73 



41-17 

 41-67 



41-40 

 41-70 



41-30 

 41-77 



41-63 

 41-97 



A" 

 B" 



41-03 

 41-67 



41-57 

 41-50 



41-00 

 42-03 



41-17 



42-03 



41-10 



42-00 



41-53 



41-83 



41-77 

 42-00 



42-00 

 42-03 



42-10 

 41-80 



42-03 

 41-63 



42-03 



41-97 



42-70 

 41-97 





According to Cyphers, the reason why the temperature of the egg rises from the 

 beginning to the end of incubation is to be found in the fact that in the early days a 

 layer of down or feathers intervenes between the body and the eggs, but as incubation 

 progresses the feathers covering the abdomen either fall off or are plucked off, and the 

 eggs are then brought into direct contact with the incubating body of the hen, " so that 

 notwithstanding the greater body temperature of the hen at the commencement of 

 incubation, the temperature of the surface which imparts the warmth to the egg is not 

 much inferior during the later stages of incubation to that of the earlier." 



From Eycleshymer's experiments it would appear that the surface temperature of 

 the hen rises gradually throughout the early days of incubation along with the tempera- 

 ture of the egg, while Cyphers says that the rectal temperature falls as that of the egg 

 rises. Both omit to mention at what hour the records were made. In my experiments 

 I find that there is practically no change in the rectal temperature of the incubating hen 

 from the commencement to the end of the period, except that it appears to rise slightly 



