THE FASTING METABOLISM. 89 
animal is explained by Voit to be due to an increasing difficulty in 
transferring the reserve fat from the adipose tissues, thus resulting 
in a diminution of the amount of fat (or its cleavage products?) 
circulating in the organism. If the body is well supplied with fat 
at the outset this phenomenon does not at first appear, and the 
ratio of proteid to total metabolism remains nearly constant for a 
time. 
With continued fasting the store of body fat is, as has just been 
shown, drawn upon much more rapidly than that of protein, while 
at the same time the total amount of the former present at the 
beginning of fasting is often less than that of the latter. As a 
necessary result, the ratio of fat to protein in the body decreases. 
When this decrease passes a certain point, the fat of the adipose 
tissue is drawn upon with more and more difficulty for material to 
supply the demand for energy, and as a result additional protein is 
metabolized to make good the deficiency of available fat. From 
this time on, the ratio of proteid to total metabolism shows a con- 
tinually accelerated increase. The time when the increase in the 
proteid metabolism becomes marked depends upon the original 
condition of the body. If the animal is well nourished, and espe- 
cially if it contains large reserves of fat, the increase may be long 
deferred or even fail to appear at all. If, on the other hand, it is 
poorly nourished and contains little fat, an increase of the proteid 
metabolism may take place almost from the outset. The following 
three examples, cited by E. Voit from Rubner’s experiments, may 
serve to illustrate these three types of fasting metabolism: 
Guinea Pig. Dog. Rabbit, 
Proteid Proteid Proteid 
Day of Metabolism Day of | Metabolism Day of at ean 
yore | ratage | ee | dsones | ee | Ga 
Des suas tis os: 10.4 2-4 16.3 3 16.5 
Sees 11.1 10-11 13.1 5-7 23.6 
BD spicata 11.0 12 15.5 9-12 26.5 
Oa eaweies 11.9 13 17.4 13-15 29.8 
eects 11.8 14 20.0 16 50.1 
Ts eee 6.9 17-18 96.4 
Si cecssitrae 11.2 
eee 10.9 
