48 BACTERIOLOGY. 



conditions under which bacteria exist in the laboratory are 

 far from being" the best. 



The spore is always formed within the cell. It may 

 therefore be spoken of as an endospore. The botanist 

 DeBary attempted to make use of this fact as the basis of 

 a natural classification of bacteria. He divided the group 

 into endospore and arthrospore bacteria. In arthrospore 

 formation it was supposed that the entire cell converted 

 itself into a spore-like resisting form. That is to say, the 

 cell-wall of the individual organism would thicken, harden 

 and become impenetrable. In this condition the cell, like 

 a spore, could survive unfavorable conditions and could in 

 turn germinate or multiply. All bacteria which were not 

 known to produce endospores were therefore placed in the 

 arthrospore group. As a matter of fact there is no good 

 and sufficient reason to believe in the existence of arthro- 

 spore formation. 



Sporulation. Owing to the extremely small size of 

 bacteria it is manifestly impossible to follow out the pro- 

 cess of spore formation in its minutest detail. This much, 

 however, can as a rule be observed. The contents of the 

 cell are at first homogeneous and the first indication of the 

 beginning of sporulation is the appearance of very fine 

 granules in the protoplasm. These are sometimes spoken 

 of as sporogenic granules. Some of these are larger than 

 others. One of these located at a certain place in the cell 

 gradually increases in size probably because the other 

 granules gather or flow together at this point. The result 

 is a roundish or ellipsoidal, bright body which at first has no 

 definite envelope or wall. Presently, however, a distinct 

 spore-wall does form which may be due to a condensation 

 of the protoplasm of the cell around the central body. At 

 all events the protoplasm of the cell disappears, as can be 

 shown by plasmolysis, and in part at least makes up the 

 substance of the spore. Occasionally a very small resi- 



