38 BACTERIOLOOY. 



The micrococci are subdivided according to their 

 grouping, as seen in growing cultures, into staphylococci 

 — -those growing in masses like clusters of grapes (see 

 Fig. 1, a); streptococci — those growing in chains con- 

 sisting of a number of individual cells strung together 

 like beads upon a string (see Fig. 1, b); diplococci 

 — those growing in pairs (Fig. 1, o) ; tetrads — those 

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

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

 contradistinction to all other forms, the segmentation, 

 which is rarely complete, takes place regularly 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 straight, rod-shaped bacteria 

 — i.e., those in which one diameter is always greater 

 than the other. 



ff ,3^' 



^>. 



a bed 



a. Bacillus subtilis with spores. 6. Bacillus anthraois 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 presents deviations from the simple 

 rod shape. Many of them in the course of develop- 

 ment 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 form- 



