112 THE FERMENTS. 



all, we know, on the contrary, that the introduction of certain forms 

 is directly harmful, and that some of the normal inhabitants of the 

 intestinal canal may under certain conditions develop distinct patho- 

 genic properties. 



General Properties of the Ferments. From what has been 

 said, it is clear that the ferments are capable of manifesting their 

 special activity even after the death of their mother-cells, and it is 

 noteworthy that a great many substances which are distinct proto- 

 plasaiic poisons do not interfere with the action of many ferments. 

 Such substances are chloroform, ether, thymol, toluol, salicylic acid, 

 arsenious acid, sodium fluoride, boric acid, hydroxylainin, glycerin, 

 etc. In the study of the ferments these bodies are of great impor- 

 tance, as we are thus apparently enabled to exclude the protoplasmic 

 activity of living cells, and to determine whether certain chemical 

 phenomena which we observe in the tissues of the body are referable 

 to the action of ferments or not. It is conceivable, however, that 

 the so-called protoplasmic poisons which do not interfere with most 

 enzymic action may subsequently be shown to be protoplasmic poi- 

 sons in consequence of their inhibitory action on enzymic processes 

 which are at present unknown, and which are of vital importance 

 to the economy. Sodium fluoride thus is a protoplasmic poison and 

 had been thought incapable of impairing enzymic processes. Loeven- 

 hart and Peirce have shown, however, that the enzymic hydrolysis 

 of esters is exceedingly sensitive to sodium fluoride, even in most 

 minute quantities. 



In this connection it is interesting to note that the blood-serum 

 contains antiferments, of the nature of which still less is known 

 than of the ferments. We can merely recognize their presence with- 

 out being able to explain their action. The existence of such anti- 

 ferments is of great biological importance, and to it such phenomena 

 as the non-self-digestion of tissues may be wholly or in part due. 

 Artificially it is possible to cause the production of antiferments by 

 immunization with the corresponding ferments. Rennin immuniza- 

 tion thus leads to the production of antirennin, pepsin to antipepsin, 

 trypsin to antitrypsin, etc., in a manner which seems quite analogous 

 to the formation of antitoxin by immunization with the correspond- 

 ing toxins. 



Other chemicals not only cause the death of the cell but also 

 arrest or annihilate the action of ferments. Such substances are 

 the bichloride of mercury, carbolic acid, 1 and to a less marked 

 degree other metallic salts, as also picric acid, tannic acid. etc. The 

 mineral acids are variable in their action. Some ferments are 

 dependent upon their presence, others behave indifferently, while 

 still others are destroyed. Some ferments are capable of destroying 

 others. The activity of the ferments is further decreased with an 

 increase of their specific products beyond a certain degree. Absence 



1 It should be noted that bichloride and carbolic acid do not interfere with all enzymic 

 processes. 



