BODY TEMPERATURE 151 



food consumed decreases with the increase in body weight 

 (table 108). Age also is probably a modifying factor, though 

 this has not been studied. In feeding under the usual conditions 

 allowance for wastage must be made. 



Tabular records for the very important studies from the labora- 

 tories of Osborne and Mendel, McCollum and many others on the 

 modifications of body growth by the use of various diets are 

 reluctantly omitted because of the general plan of presenting in 

 these pages data for the normal rat only. 



The literature given under "Physiology: References" at the 

 end of the chapter contains the citations by authors and dates 

 grouped in accordance with the following scheme. 



9. Nutrition general. Quantitative deficiency. 



(a) Tests with: Proteins, Fats, Carbohydrates, Salts, Vitamines. 



(6) Effects on systems and functions, (a) Osseous system, (ai) 

 Reproductive system; (b) Reproductive function. 



(c) Body temperature. Using the mercurial thermometer in the 

 rectum, Pembrey ('95) reports a body temperature of 37.5C. 

 in adult Albinos. Macleod ('07) by the same method finds a 

 range of 37.5-38.5C. with a mean of 37.9C.; Congdon ('12) 

 also by the same method a temperature of 37.9C. in the young; 

 in the adult, when reared at 16C., a temperature of 36.2C. 

 and when reared at 33C., of 37.2C. 



The newborn rat is very responsive to changes in the external 

 temperature. Temperature regulation is established at about 

 10 days of age but is never perfect, even at maturity. The 

 female has a somewhat higher temperature than the male, the 

 excess for the female amounting to 0.74C. in rats about 25 

 days old (Bierens de Haan, '22). There is a tendency for the 

 body temperature to rise in the afternoon. 



Graham and Hutchison ('14) using the thermoelectric method 

 of Philips and Demuth, obtained the following ranges according 

 to changes in the external temperature table 1 10. 



Bierens de Haan ('22) found the morning temperatures of 

 young albino rats to be as in table 111. 



