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XXI. — Observations on the Body Temperature of the Domestic Fowl (Gallus gallus) 

 during Incubation. By Sutherland Simpson, M.D. (From the Physiological 

 Laboratory, Medical College, Cornell University, Ithaca, N.Y., U.S.A.) 

 Communicated by Professor E. A. Schafer, F.R.S. 



(MS. received November 7, 1910. Read December 5, 1910. Issued separately January 13, 1911.) 



Introduction and Experiments. 



It is held by many that the body temperature shows certain fixed diurnal and seasonal 

 variations which cannot be accounted for by the action of the various influences, such 

 as muscular exercise, ingestion of food, sleep, etc., which are known to affect the rate 

 of heat production and heat loss. These variations are believed to be associated with 

 corresponding changes in the tissue activities, and to a large extent to be independent 

 of environmental conditions. 



In this relation it is important to study the body temperature in association with 

 the seasonal and other changes of habit which all animals exhibit to a greater or less 

 degree, and, amongst homoiothermic animals, no class shows greater evidence of cyclical 

 bodily changes than do birds. During moulting time, in the late summer and autumn, 

 they shed their feathers and show other signs of depressed vitality, while in the spring, 

 in preparation for the mating and breeding seasons, they put on fresh plumage and 

 become extremely active. Then again during the incubation or brooding period the habits 

 of the female bird, and in many cases also of the male, become greatly changed and the 

 bodily activities profoundly modified. 



No systematic investigation, so far as I know, has been made into the relationship 

 which may exist between the body temperature of birds and these seasonal changes of 

 habit, and although the whole problem is an extensive one calling for much detailed 

 study, still, the effects of the natural alteration in the daily routine which takes place 

 during the nesting or incubation period may be easily determined in the case of the 

 domestic fowl. 



It is a popular belief that the temperature of a brooding hen is above the normal ; 

 she is supposed to have " broody -fever." This I have gathered from conversations with 

 poultrymen and farmers both in this country and in Scotland. That this should be the 

 case seemed to me improbable, and to satisfy myself on the question I have made, 

 within the last three years, three series of observations on the rectal temperature 

 of brooding hens [Gallus gallus) and a fourth series has been made for me by 

 Mr W. G. Krum, in charge of the poultry house in the Agricultural College, Cornell 

 University. 



TRANS. ROY. SOC. EDIN., VOL. XLVII. PART III. (NO. 21). 90 



