FERMENTS, ENZYMES, TOXINS AND PTOMAINS 59 



stood, but it has been aptly suggested that they may be 

 fundamentally analogous to the specific positive and negative 

 affinities exhibited by the ions resulting from dissociation 

 of electrolytes, and that they may "have their explanation 

 in the forces of ionic attraction and repulsion." In this 

 connection it is important to note that the wandering 

 cells of the animal body, the leucocytes, exhibit also these 

 chemotactic phenomena; and it is especially necessary to 

 a complete comprehension of the process of suppuration to 

 bear in mind that among the substances which have the 

 greatest attraction for these wandering cells, are the products 

 of growth of certain bacteria in some cases, and the protein 

 constituents of the bacteria themselves in others. 



To summarize briefly the foregoing it may be said, in 

 general, that for the growth and development of bacteria 

 nitrogenous organic matter of a neutral or slightly alkaline 

 reaction, in the presence of moisture and at a suitable tem- 

 perature, is all that is necessary. From this can be formed 

 some idea of the omnipresence in nature of these minute 

 vegetables. Bacteria are found wherever these conditions 

 obtain. 



^ Read Sewall on Some Relations of Osmosis and Ionic Action in Clinical 

 Medicine, International Clinics, vol. xi. Eleventh Series. 



