GROWTH AND DEVELOPMENT OF BACTERIA. 45 



note that the wandering cells of the animal body, the 

 leucocytes, exhibit also these chemotactic phenomena ; 

 and it is especially necessary to a complete comprehen- 

 sion 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 protoplasmic con- 

 stituents of the bacteria themselves in others. 



From what has been learned, it may be said, in 

 general, that for the growth and development of bacteria 

 organic matter of a neutral or slightly alkaline reaction, 

 in the presence of moisture and at a suitable tempera- 

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

 some idea of the omnipresence in nature of these minute 

 vegetables. Wherever these conditions obtain bacteria 

 may be found. 



