OUTLOOK. 669 



treated previously with horse's blood will not react, for example, upon 

 the blood of the ox, sheep, or goat. We may add that the formation of such 

 specific products is not peculiar to the blood and its serum. The property 

 is common to all the cells, body-fluids, and secretions. If we inject the 

 spermatozoa of the sheep into a rabbit, the blood-serum of this animal 

 when added to the living, motile spermatozoa of the sheep will restrict their 

 activity. And this serum also has a solvent action upon the blood-corpus- 

 cles of the sheep's blood; i.e., the effect of the spermatozoa is the same as 

 if sheep-blood itself had been injected. Hamburger assumes that every 

 cell, and all the other substances which circulate in the body-fluids, possess 

 definite atomic groupings, which we must regard as imparting the specific 

 nature to these products. Consider the ferments! These are substances 

 of which we know merely the effect. Emil Fischer has, as we have often 

 mentioned, called our attention to their very specific action, and indicated 

 clearly their dependence upon the configuration of the different compounds 

 with which they react. The ferment molecule must possess certain definite 

 groups by reason of which it can react with certain other molecules, 

 and only these. Fischer has aptly compared the relation between the 

 ferment and the compound with which it reacts as that of a key, and the 

 lock which it fits. Just as a given key fits only a certain kind of lock, and 

 conversely the lock can only be opened by just such a key, so the specific 

 atomic grouping of the ferment molecule probably harmonizes exactly 

 with the compound to be acted upon. We can easily imagine that slight 

 changes in the arrangement of the atoms in the ferment molecule will be 

 sufficient to modify the efficiency of the ferment. On the other hand, we 

 can also believe that when this characteristic group is in combination with 

 some other substance, the ferment will be prevented from exercising its 

 function. It is possible that the zymogen stage of the ferment is brought 

 about by some such combination or different arrangement of the atoms 

 in the ferment molecule. These views are advanced merely to indicate 

 that just as the individual cells can produce ferments, they them- 

 selves may be endowed with specific atomic groups, which, as Ehrlich 

 has suggested, may perhaps stand in certain relation to the assimilation 

 of the food. In this case there would be a certain analogy between fer- 

 mentation and cell-activity. We know of the formation of anti-ferments 

 when the ferments are introduced into the circulation. These anti- 

 ferments are also specific in their action. We may look upon the forma- 

 tion of the precipitins, and related bodies, as taking place in a perfectly 

 analogous manner. We introduce into the blood and cells of a foreign 

 species of animals a certain atomic grouping which is peculiar to a different 

 species, and which is perfectly foreign to the first animal. The animal 

 organism reacts towards this exactly in the same way as towards the 

 toxines which result from micro-organisms. Substances are evidently 



