38 BAGTERlOLOar. 



sisting of a number of individual cells strung together 

 like beads or pearls upon a string (see Fig. 1, i); 

 diplococd — those groMdng in pairs (Fig. 1, c); tetrads 

 — those developing as fours (Fig. 1, d); and sarcina — 

 those dividing into fours, eights, etc., as cubes — that is, 

 in contra-distinction to all other forms, the segmenta- 

 tion, which is rarely complete, takes place in three 

 directions of space, so that when growing the bundle of 

 segmenting cells presents somewhat the appearance of 

 a bale of cotton (Fig. 1, e). 



To the bacilli belong all rod-shaped organisms, i. e., 

 those in which one diameter is always greater than the 

 other. 



Kg. 4. 



-Y' v^ ^^ }> 



ah c d 



a. Bacillus subtilla with spores. 6. Bacillus anthracls with spores, c. Clos- 

 tridium form with spores, d. Bacillus of tetanus with end spores. 



In this group are found those organisms the life cycle 

 of many of which present deviations from the simple 

 rod shape. Many of them in the course of development 

 increase in length into long threads, along the course of 

 which traces of segmentation may usually be found — 

 the anthrax bacillus and bacillus subtilis are conspicuous 

 examples of this. Again, under certain conditions, 

 many of them possess the property of forming within 

 the body of the rods oval, glistening spores (see Fig. 4), 

 and if the conditions are not altered the rods may 

 entirely disappear, so that nothing may be left in the 

 culture but these oval forms. In some of them this 



