i EXCHANGE OF MATEEIAL 23 



are highly developed. In fresh water it remains in a fasting 

 condition for from six to nine-and-a-half months, and during this 

 long period of inanition the muscles of the back become very 

 much smaller, while the testicles and ovaries develop enormously. 

 In this case, therefore, inanition acquires the importance of 

 a genuine physiological function, having as its object the 

 development of the sexual organs at the expense of the other 

 tissues and the maintenance of the essential function of 

 reproduction. 



The general conclusion to be drawn from all investigations 

 into fasting in animals and men is that there are two fundamental 

 conditions, if life is to last for a long time without an external 

 supply of food : (a) there must be a certain provision of oxidisable 

 materials stored up in the organism before the fast begins ; 

 (6) a greater economy must be exercised in the absorption and 

 consumption of these materials. In inanition life lasts for a 

 shorter time because there is little economy, whereas in hibernation 

 expenditure is reduced to a minimum, and life, therefore, lasts for 

 an almost incredible length of time. 



It is important to examine the course of the total consumption 

 of the organism during fasting under conditions as far as possible 

 uniform, in order to avoid the disturbances caused by variations in 

 external temperature, muscular work, etc. For this purpose the 

 curve of weight is constructed from the data collected carefully 

 every day at some fixed hour after the bladder has been emptied. 

 According to my own observations both in the case of dogs and 

 of Succi, the course of the curve of weight during the long period 

 of physiological inanition is extremely regular, and corresponds 

 approximately to that of an equilateral hyperbole, the equation 

 differing according to the individual and his initial weight. On 

 the other hand, the curve deviates from the hyperbolic, and shows 

 irregularities both during the initial period of hunger and during 

 the final period of crisis which precedes death. 



This fact proves that the organism possesses some mechanism 

 which regulates the losses suffered daily during starvation. This 

 is the mechanism which normally regulates the production and 

 loss of heat, and we shall study it in the next chapter. So long 

 as the curve of weight follows the regular hyperbolic course, the 

 regulators are working well ; when it deviates from this course, 

 as during the periods of hunger and crisis, they work badly, 

 finally fail, and thus bring about the death of the organism. 



VI. For the determination of the quality and quantity of the 

 material consumed daily during starvation, the quantitative 

 analysis of the chemical products contained in the urine, and the 

 carbon dioxide discharged from the lungs and skin, is as indis- 

 pensable as in the case of ordinary nutrition. From the quantity 

 of nitrogen we can deduce the quantity of protein consumed ; from 



