196 PHYSIOLOGICAL CHEMISTRY 



Starvation. If an animal is deprived of food it will live for 

 some time, drawing upon its own tissues for the essential ma- 

 terials for fuel and body maintenance. The length of time an 

 animal will survive without food varies greatly with the size 

 and condition of the animal, in general a large or a fat animal 

 will survive longer. It depends also much on external condi- 

 tions. If exposed to cold or great exertions as in winter, in 

 shipwreck, etc., life may be lost in a few hours. Otherwise, fast- 

 ing may be continued for even a month or longer in the case of 

 a man, without death ensuing. Children die much sooner, 

 usually in four or five days. Recently the case of a dog was 

 reported in which the animal survived 117 days of fast. If 

 water is withheld as well as food, death occurs in a few days' 

 time. 



The study of metabolism during fasting furnishes interesting 

 information about the chemical processes going on in the body. 

 Benedict has published an exhaustive, study of a man fasting 31 

 days. 



During fasting there is of ocurse continuous loss of body 

 weight. Reserve stores of glycogen and fat are called upon, but 

 there also is a continuous excretion of nitrogenous material in 

 the urine, showing that some protein is continually broken down. 

 At an earlier point we have noted the appearance of creatine in 

 starvation, replacing a portion of the normal creatinine. A most 

 interesting fact is that all tissues and organs do not lose weight 

 in like amount as starvation proceeds. Organs of vital impor- 

 tance such as the heart, the brain and nerves are preserved prac- 

 tically without loss of weight, whereas the skeletal muscles, the 

 liver (loses glycogen) and adipose tissue lose a very considerable 

 portion of their weight. The body tries to save the most vitally 

 important organs, and does so at the expense of less indispen- 

 sable tissues, which are called upon to furnish fuel and undoubt- 

 edly also repair material for the vital parts. 



The nitrogen excretion of a fasting animal gradually de- 

 creases as time goes on, probably as a result of the decreased 

 amount of protein tissue in the body. Shortly before the death 



