BACTEEIA 



C55 



of the same : A is a group of attached filaments ; B to H show por- 

 tions of spiral filaments ; C, D, F, to H represent the act of division 

 into smaller fragments but without motion ; in H the separate 

 cells are distinctly showTi ; E shows the separation of a complete 

 spirillum form possessed of flagella and capable of great activity. 



Bacteria may be united by some interfusing gelatinous material 

 in which all action ceases or is of the most limited kind ; and these 

 living films, which appear on the surface or suspended in the interior 

 of putrescent fluids, are 

 known as Zooglw. 

 They may also be found 

 on the surfaces of solid 

 bodies, where the putre- 

 factive ferment is in 

 action. 



Bacteria have been 

 divided into two classes, 

 distinguished by the 

 formation of endospores 

 in the one and of arthro- 

 spores in the other. 



I. The endosporous 

 forms are those whose 

 multiplication is brought 

 about by the formation 

 within a cell of a minute 

 globular or oval body, 

 which, while the sur- 

 rounding protoplasm of 

 the mother-cell is assimi- 

 lated, gradually reaches 

 its mature condition. 

 What it is that exactly 

 determines the act of 

 spore-formation is not 

 known, but it is probable 

 that free access to oxygen 

 constitutes an important 

 factor. 



A chosen illustration 

 of the endosporous Bac- 

 teria is Bacillus mega- 

 therium. It was first 



observed on boiled cabbage leaves, and is considered by De Bary as 

 an 'exceedingly instructive form.' It is 2'5/u in short diameter and 

 about four times as long as this. It is illustrated in fig. 489. a re- 

 presents a motile chain of the Bacilli in active vegetation. This is 

 magnified 250 diameters, b two active rods magnified 600 diameters. 

 p shows the result of treating a form in the condition b with an 

 alcoholic solution of iodine, c is a rod with five cells preparing to 

 form spores, d to /represent successive stages of a pair of rods in 



FIG. 488. Beggiatoa alba, curved and spiral 

 forms. (From De Bary's ' Comparative Morpho- 

 logy of Fungi.') 



