50 BACTERIOLOGY. 



To the fspirilla belong all organisms that are curved 

 when seen in short segments, or when in longer threads 

 are twisted in the form of a corkscrew. (See Fig. 4.) 



The micrococci are subdivided according to their pre- 

 vailing mode of grouping, as seen in growing cultures, 

 into staphylococci — those growing in masses like clusters 

 of grapes (see Fig. 2, a) ; streptococci — those growing in 

 chains consisting of a number of individuals strung 

 together like beads upon a string (see Fig. 2, b) ; diplo- 

 coGci — those growing in pairs (Fig. 2, c) ; tetrads — those 

 developing as fours (Fig. 2, d) ; and sarcinoe — 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. 2, c). 



To the bacilli belong all straight, rod-shaped bacteria 

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

 than the other. 



Fig. 5. 



i(i Vy» >v. AV 



a b e d 



a. Bacillus subtilis with spores, b. Bacillus anthracis 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 

 development increase in length into long threads, 

 along wliich traces of segmentation may usually be 



