generally defends itself, by means of ferments, against compounds that are capable of decomposition and that consist of many elements. New, too, is the idea that by means of these ferments we can judge as to the functions of particular organs. Finally, the idea that the animal organism sets free specifically directed ferments, and that, in so doing, it registers the fact that the components of its various kinds of cells have an exclusive structure corresponding to each kind of cell, is also new.
Objection has been taken to the idea of strictly and specifically directed ferments on the ground, that it is impossible to accept the idea that specific reactions take place, because the so-called "antitryptic power" of Henkel-Rosenthal, the "cobra-poison hæmolysis" of Heynemann, and finally the "catalysator influence" of Weichardt, are not specific. It is forgotten that the fermentative decomposition represents the primary activity, and that those substances, which are in question in the above-mentioned methods, are produced secondarily by the defensive ferments. That, during the process of decomposition, the original characteristic structure of a compound is soon destroyed, we have repeatedly affirmed. All possible stages of decomposition, of the most different origin, can in many respects act identically. Thus, for instance, it is possible to prove conclusively that the hydrolysis of the dipeptide, d-alanyl-glycin, can be
