26 Manual of Veterinary Microbiology. 



but there are bacteria in which the division takes 

 place in two crossed directions (micrococcus tetra- 

 genus), or even in three directions (sarcina) ; in this 

 last case the bacteria, the secondary elements of which 

 remain united, take the form of a cube. 



3. Sporulation. — Multiplication by fission appears to 

 be the only mode possessed by microbes of spherical 

 form; in the majority of others we recognize a second 

 mode, — sporulation (13). This consists in the forma- 

 tion within the bacteria of brilliant points which are 

 apparently the result of a condensation of the orig- 

 inal protoplasm, whilst^the latter at the same time be- 

 comes very clear. These brilliant points are the 

 spores ; they are set at liberty by the destruction of 

 the cell which has produced them and when they 

 find themselves in good conditions of temperature and 

 humidity, and in a suitable medium, they reproduce 

 the bacteria as, in the higher forms of vegetation, the 

 seed gives origin to the entire plant. 



Spores show a remarkable resistance to the action 

 of the common causes of destruction of microbes. 

 They almost never develop in the media in which they 

 have taken birth. 



Botanists recognize, besides fission, which for them 

 is only a form of growth, or vegetation, two methods 

 of sporulation or fructification. The first and best' 

 known is endosporulation which we have just described; 

 the second which it is not always easy to distinguish 

 from fission has received the name arthrosporulation. 

 It is characterized by the production by fission, at the 

 expense of cells performing the function of repro- 

 ductive elements, of new cells which differ from those 

 obtained by ordinary fission by their state of latent 



