334 



A TEXTBOOK OF PHYSIOLOGY 



what is causing the low respiratory quotient of the starving animal. 

 It may be partly accounted for by the elimination of acetone bodies 

 in the urine (see p. 468). When the store of fat is exhausted, the 

 protein consumption and the urea output goes up and the end is then 

 near. 



During starvation, the urine becomes considerably lessened in 

 amount. Salts continue to be excreted, the amount of sodium 

 chloride being markedly decreased, but that of potassium, calcium, 

 magnesium, and phosphates increased. This is due to tissue destruc- 

 tion, especially of the bony tissues. Life persists at the expense of what 

 may be termed the less important tissues and organs, as can be seen 

 from the following table : 



MALE CAT. 



Adi |K iso tjssuc 

 Spleen . . 

 Liver 

 Testicles 

 Muscle- 

 Kidneys 

 Skin 

 Intestine- 

 Lungs . . 

 Pancreas 

 Hones . . 

 Heart . . 

 Brain 



97 per cent, loss of weight. 



67 



f>4 



40 



31 



26 



21 



is 



18 



IT 



14 



An outstanding feature in starvation is the manner in which the 

 blood, although somewhat decreased in amount, is kept more or less 

 constant in composition. 



A similar principle applies to those animals which undergo periods 

 of voluntary abstention from food. Previous to such periods they 

 make special provision by storing up large supplies. One particularly 

 interesting example is the salmon. While living in the sea, the food- 

 supplies are taken in and stored as protein and fat chiefly in the 

 tail muscles and the fat depots of the body. During the migration 

 up-river to the " spawning-ground," which lasts several months, no 

 food is taken in, and the whole of the energy, spent in swimming 

 and in the development of the sex organs, takes place at the expense 

 of these food-supplies. 



Animals which hibernate also lay up a store of food previous to 

 and live at the expense of this during the period of hibernation 

 (see pp. 439. 440). 



Lack of Water. The living processes of protoplasm are dependent 

 on its water content. Water has been found to form 66 per cent, 

 of the entire body of a well-fed ox, 57-9 per cent, of a well-fed 

 pig, and 63-2 per cent, of a well-fed sheep. Since it is continuously 

 leaving the body in the urine, breath, sweat, and other secretions, 

 it onust be replaced. The amount of water lost under average 

 conditions of temperature and humidity is about 1-25 per cent, of 

 body weight during rest and hunger, 1-32 per cent, during rest 

 and average diet, and 2-91 per cent, during hard work and average 



