CHAPTER 4 

 PHYSIOLOGY 



1. Muscle and nerve. 2. Nervous system, a) Central, b) Peripheral, b 1 ) 

 Degeneration, b 2 ) Regeneration. 3. Special senses. 4. Blood and lymph. 5. 

 Circulation — blood and lymph. 6. Respiration. 7. Digestion and secretion 

 (exclusive of ductless glands). 8. Nutrition, a) Body temperature. 9. Repro- 

 duction. 10. Endocrine system. 



The quantitative data for the functions of the normal Albino 

 are rather scanty. Those available are given in their topical 

 order and the references at the end of the chapter are also ar- 

 ranged by topics — as usual. 



Tabular records for the very important studies of Osborne 

 and Mendel on the modifications of body growth by the use of 

 various proteins are reluctantly omitted because of the general 

 plan of presenting in these pages data for the normal rat only. 



8. Nutrition. A study of the nitrogen excretion has been 

 made by Hatai ('05). Chicago Colony, ration: Uneeda biscuit 

 and water. 



From observations on 89 male rats at different ages and weights the 

 following results were obtained: 



1. The total amount of urine increases with the weight up to 120 

 grams, then decreases very decidedly. From 180 grams it again in- 

 creases up to 220 grams, beyond which weight it remains rather constant. 

 A diminution of urine in animals between 120 and 180 grams, or ap- 

 proximately 70-125 days old, seems to be a normal phenomenon rather 

 than mere statistical variation. Whether or not this is a phenomenon 

 of adolescence needs further investigation. It must be noted, how- 

 ever, that puberty in the rat begins at about seventy days after birth. 

 The smaller animals excrete a relatively greater quantity of urine than 

 the larger animals. 



2. The total amount of nitrogen is quite independent of the amount 

 of urine, and increases constantly and continuously throughout life. 

 The smaller rats, however, excrete a relatively greater quantity than 

 the larger animals. 



3. The percentage value of urinary nitrogen is 91 per cent of the 

 total in the case of smaller animals, and 89 per cent in the case of the 

 larger. 



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