40 THE GERM THEORY OF DISEASE. 



apparent scavengers became the destroyers of living structures, 

 and there was still a large number of workers who believed 

 that the distinctive features of these organisms could and 

 would be developed in the course of time, and they continued 

 the work steadily and firmly. 



MODES OF PEOPAGATION. 



Knowledge of these organisms was gradually extended. 

 They were gradually divided into groups, according to their 

 forms and modes of propagation. They have been found to 

 multiply in three different ways. 



1st. By simple budding, as in the yeast plant. 



2d. By fission, in which one individual simply divides 

 into two. 



3d. By true spores or eggs, developed in their interior, as 

 eggs are developed in the interior of the segments of the 

 tapeworm. 



The forms are quite numerous. The round and oval forms 

 are called micrococci, and the short, stem-like forms bacilli ; 

 the spiral forms spirilli ; while a large number remain with 

 the common name bacteria connected with a descriptive 

 adjective, as bacteria termo. 



More recently the name of the disease found to be, or sup- 

 posed to be, produced by the particular form has been 

 attached, as bacillus anthrax, bacillus tuberculosis, etc. 



Many other names have been used, but those given seem 

 now to be taking their places.* 



* Any one who wishes to study these forms particularly should have 

 Cohn's Classification, which is the most complete yet made out, and will 

 doubtless serve as the basis of all future efforts in this direction. Magnin, 

 in his little book, " Bacteria," gives this classification in very convenient 

 form. 



