CHAPTER XX. 



HIGHER BACTERIA AND FUNGI PATHOGENIC FOR ANIMALS. 



General consideration. In the study of animal diseases 

 a number of morbid conditions have been found which were 

 produced as a result of the invasion of the tissues with certain 

 organisms belonging to plant life more complex in structure 

 than the lower bacteria. There is considerable confusion in 

 the classification of these organisms. Some of the forms placed 

 by Migula in the higher bacteria are classed by others among 

 the fungj. Because of this confusion and the very few species 

 that require consideration here, the organisms will be referred 

 to in the genera under which they have been described without 

 further attempt at classification. 



The higher bacteria seem to stand in the process of devel- 

 opment between the lower bacteria and the more highly de- 

 veloped fungi. In this connection it is important to recognize 

 that certain bacteria such as those of tuberculosis, diphtheria, 

 glanders and other forms in which branching sometimes occurs, 

 are considered by a few writers as belonging to the strepto- 

 thrices. The genera more commonly recognized as containing 

 pathogenic forms are defined as follows : 



LEPTOTHRIX. 



This genus includes those forms which appear as simple 

 threads without branches. 



The leptothriches have been found in lesions of the mouth 

 in the human subject. They have been cultivated only with 

 difficulty. The genus seems to have little or no pathogenic 

 significance for the lower animals. 



ACTINOMYCES. 



The actinomyces include those organisms which grow in 

 the form of threads with true branching. They are charac- 



