DIGESTION OF FOOD. 351 
principles actually do explain the whole, which we do not grant, 
it would by no means follow that such was the natural behav- 
ior of this organ in the discharge of its ordinary functions. 
When we consider that the blood tends to maintain an equi- 
librium, it must be evident that the removal of substances from 
the alimentary canal, unless there is to be excessive activity of 
the excretory organs and waste of energy both by them and 
the digestive tract, must in some degree depend on the demand 
for the products of digestion by the tissues. That there is to 
some extent a corrective action of the excretory organs always 
going on is no doubt true, and that it may in cases of emergency 
be great is also true; but that this is minimized in ways too 
complex for us to follow in every detail is equally true. Diges- 
tion waits on appetite, and the latter is an expression of the 
needs of the tissues. We believe it is literally true that in a 
healthy organism the rate and character of digestion and of 
the removal of prepared products are largely dependent on the 
condition of the tissues of the body. , 
Why is digestion more perfect in overfed individuals after 
a short fast ? The whole matter is very complex, but we think 
it is infinitely better to admit ignorance than attempt to ex- 
plain by principles that do violence to our fundamental con- 
ceptions of life processes. To introduce “ferments” to explain 
so many obscure points in physiology, as the conversion of 
peptone in the blood, for example, is taking refuge in a way 
that does no credit to science. 
Without denying that endosmosis, etc., may play a part in 
the vital processes we are considering, we believe a truer view 
of the whole matter will be ultimately reached. In the mean 
time we think it best to express our belief that we are ignorant 
of the real nature of absorption in great part; but we think 
that, if the alimentary tract were regarded as doing for the 
digested food (chyle, etc.) some such work as certain other 
glands do for the blood, we would be on the way to a truer con- 
ception of the real nature of the processes. 
It would then be possible to understand that proteids either 
in the form of soluble or insoluble substances, including pep- 
tone, might be taken in hand and converted by a true vital 
process into the constituents of the blood. 
If we were to regard the kidney as manufacturing useful 
instead of harmful products, the resemblance in behavior would 
in many points be parallel. We have seen that mechanical 
explanations of the functions of the kidney have failed, and 
