IMMUNITY. 175 



and by which the cellulose of the tree is digested. After a time these 

 ferments digest not only the cellulose of the tree but also the older 

 parts of the mould itself. The action of bacterial enzymes of this 

 class is offered as an explanation of the degeneration forms observed 

 in many old bacterial cultures. From such cultures there may be 

 precipitated with alcohol an albuminous body which when dissolved 

 in feebly alkaline solution has a bacteriolytic effect. Arrest of 

 growth in artificial cultures occurs when the solution of the bacteri- 

 olytic enzyme is sufficient to digest newly formed bacteria. The 

 same phenomenon is offered as an explanation of the self-limitation 

 of the infectious diseases. When the bacteriolytic enzyme formed in 

 the animal body has reached a sufficient degree of concenti-ation to 

 dissolve the bacteria which have produced it, further growth of the 

 organism is impossible, and the disease is arrested. It is probable 

 that the enzyme exists in the bacterial cell as a zymogen, and is able 

 to manifest its digestive action only after liberation from the cell 

 contents. The enzyme produced by a given bacillus may dissolve 

 the cell membrane not only of the bacterium which has produced it, 

 but of other bacteria as well. These enzymes are divided into two 

 classes, which are known as conforme and heteroforme, the former 

 being one which dissolves only the bacterium which produced it, while 

 the latter is one which has a bacteriolytic action upon other micro- 

 organisms as well. It is proposed that bacteriolytic enzymes be 

 given the general name of nucleases, because they digest the nucleo- 

 proteids of the bacterial cells. Special enzymes are designated by 

 names derived from those of the bacilli which produce them. Thus 

 the bacteriolytic enzyme of the bacillus pyocyaneus is known as pyo- 

 cyanase ; that of the cholera vibrio as cholerase, etc. It is supposed 

 that in the living body the enzymes of pathogenic bacteria combine 

 with certain albuminous bodies, probably those derived from the leu- 

 cocytes. The substances resulting from these combinations are desig- 

 nated immuneproteids, and one of these is distinguished from the 

 others by prefixing the name of the special enzyme. Thus we 

 have pyocyanase-immuneproteid, cholerase-immuneproteid, typhase- 

 immuneproteid, etc. 



Emmerich and Low have shown experimentally that pyocyanase 

 readily destroys and dissolves anthrax bacilli in vitro, both under 

 aerobic and anaerobic conditions. They have also shown that rab- 

 bits inoculated with virulent cultures of anthrax do not die if they 

 be treated with solutions of pyocyanase. In these experiments the 

 animals received their first treatment simultaneously with the inocu- 

 lation or directly afterward, and subsequent treatments were also 

 given. They were not able to immunize rabbits to anthrax by pre- 

 vious treatment with solutions of pyocyanase. However, they did 

 succeed in preparing artificially pyocyanase-immuneproteids with 

 which immunity to anthrax was secured. In these experiments con- 



