Page:Popular Science Monthly Volume 72.djvu/407

 influence of alcohol on this oxidizing ferment which is normally charged with the destruction of any surplus of this deleterious substance. Here we have a definite and logical explanation of an abnormal condition where interference with the routine action of a tissue ferment or enzyme is one of the specific causes of the disturbance.

This is one of many illustrations that might be cited showing how alterations in the environment of the enzymes occurring in the body may modify the rate of action, either by stimulation or inhibition, and thereby pave the way for marked disturbances of nutrition. It is easy to see also how the many enzymes which rule the normal nutritional processes of the body may need control in order to prevent undue activity, or excessive enzymolysis, with consequent disturbance of the normal nutritional rhythm. Nature has apparently provided this protection by a row of anti-bodies widely distributed which serve as specific antiferments, and either prevent undue alteration or check entirely the action of a given enzyme in certain localities where its action would be detrimental. We find illustrations of such antiferments in the gastro-intestinal tract, by the presence of which the digestive enzymes are restrained from attacking the proteins of the tissue cells, composing the lining membranes of the intestine. Apparently, there is no reason why the enzymes pepsin, trypsin, etc., which digest so vigorously the various protein foodstuffs should not attack with equal avidity the related proteins present in the mucous membranes of the stomach and small intestine. This, however, does not occur during life, no matter how strong the digestive fluids that are secreted into the digestive tract, partly at least because of the inhibitory effect of the natural anti-bodies that are present in the membranes. Again, it is interesting to note that just as antitoxins are produced in the animal body by the injection of a proper amount of toxin into the system, so likewise antiferments can be formed by injection subcutaneously of specific enzymes. Thus, as Morgenroth found, if the enzyme rennin which coagulates milk be injected under the skin of an animal in small doses, after a time the blood serum of the animal so treated will contain something which hinders or prevents the coagulation of milk. In other words, an anti-rennin is formed, just as under similar conditions an antitoxin may be produced. We thus see a close similarity or analogy between the production of a specific immunity toward a given toxin and the formation of antiferments.

Finally, we may again emphasize the specific character of the many ferments that play such an important part in the nutritional processes of man and the higher animals. We readily understand that an enzyme capable of acting upon proteins is quite ineffective when brought in contact with a carbohydrate, or that an enzyme able to digest one form of sugar can not attack even a closely related sugar belonging