CHAPTER 4 

 PHYSIOLOGY 



1. The rat compared with man (a) Technique. 2. Muscles and neives. 

 3. Nervous system. 4. Special senses. 5. Circulation. 6. Blood and lymph. 

 7. Respiration. 8. Metabolism. 9. Nutrition (a) Tests, (b) Effects on systems 

 and functions, (c) Bodj^ temperature, (d) Calorimetry. 10. Reproduction and the 

 sex organs. 11. Exocrine system: General. 12. Endocrine system. 13. Pineal 

 gland. 14. Hypophysis. 15. Feeding endocrine glands. 



1 . The rat co7npared with man. In order to have a background 

 for the mterpretation of the physiological responses of the rat, 

 it is desirable to indicate its relations to man. If the data for the 

 relative weights of the different systems in the man (69.7 kilos) 

 Bischoff ('63) are compared with those of the one year old rat 

 (Jackson and Lowrey, '12) the relations are as in table 89. 



Table 89 shows that in man the skeleton is relatively heavy. 

 The small weight of the skin depends in part on the relative 

 diminution of the surface area in the larger animal, man — 

 a factor which tends to reduce the relative weight of the skin. 

 The massive fat was weighed as one part, in the case of man, 

 but not similarly handled in the case of the rat. Allowing for all 

 of these differences, there remains a fair correspondence between 

 the two forms in the proportionate weights of the musculature 

 and the viscera. 



In the case of the viscera, however, the individual organs do 

 not stand in the same relations. I have sought to illustrate this 

 by the data presented in table 90. Here the weights of several 

 organs taken from the tables for the rat, tables 144, 145, 146 

 and 148, are transformed into those to be expected in a man of 

 65 kilos, if the percentage relations were those in the rat. These 

 computations are controlled by the data for the observed weights 

 in man, obtained from various sources. 



In this comparison it appears that in man the lungs, heart, 

 brain, spleen and thyroid are heavier, while the remaining organs 



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