INFECTION AND INTOXICATION. 5 



actual false membrane. An extraordinary feature exhibited 

 by the diphtheria toxin is seen in the extreme slowness with 

 which it is sometimes known to act. Whereas the poisonous 

 chemical agents with which we were previously acquainted 

 exert their effect quickly, and usually after a short interval, 

 the diphtheria toxin requires at times weeks and even months 

 for the production of fatal results in the animal inoculated. 

 For a time it stood alone in this regard, but I have found 

 similar delay in the action of another toxalbumin, — ricin, a 

 substance yielded by the seeds of the ricinus communis (castor 

 plant). 



Recent studies have shown that the toxalbumins are widely 

 distributed in nature. Thus far they have been found among 

 the lower and higher vegetable forms, and even in the blood of 

 various animals, such as the eel, snake, and dog. 



When we proceed to study the effects of these pathogenic 

 agents upon the animal body, we find that the phenomena 

 which are caused by the toxins can often be distinguished 

 from those due to the actual presence of the bacteria themselves. 



Two main forms of lesions of cells can be distinguished in 

 infectious diseases. In the one, most or all of the cells are 

 affected ; the lesion is diffuse, and shows itself by an increase 

 in the size and granulations of the cells, associated often with 

 the appearance of globules of fat in those otherwise free from 

 this substance, or with an increase of it in those already con- 

 taining it. In this way is brought about the so-called paren- 

 chymatous degeneration of cells, which in extreme cases may 

 lead to actual cell death (necrosis). This is the typical lesion 

 ascribed to the action of chemical substances. It is found in 

 all infectious diseases and in many forms of intoxication. 



More interesting are the so-called focal lesions, of which it 

 may be said that certain ones are caused by bacteria and 

 others by toxic substances. As an example of the former, a 

 small abscess may be taken. The bacteria which are most 

 commonly associated with this pathological process are cocci, 

 which grow in grape-like clusters presenting often, when cul- 

 tivated on artificial media, a golden-yellow color, whence the 

 name " Staphylococcus pyogenes aureus." If a section be 



