156 CLASSIFICATION OF THE MICRO-ORGANISMS. 



Various 



vegetative 

 forms. 



Spores. 



tinguished from the former as staphylococcus. Other 

 fission fungi grow in the form of rods, the longitudinal 

 diameter being markedly greater than the transverse; 

 for this form the term bacillus is employed. (Formerly 

 a distinction was made between the shorter rods, 

 bacterium, and the longer rods, bacillus, in which the 

 one diameter is more than two or three times greater 



t f* 



Involution 

 forms. 



r -o , 



:,* 



Fig. 3lB. Various vegetative forms X 700. 



, bacilli ; b, clostridium ; c, threads, pseudo-threads ; d, apparent 

 branching ; e, vibrio ; f, spirillum ; g, spirochaete ; h, spores. 



than the other.) Bacilli which are swollen in the middle 

 or spindle-shaped have the special name clostridiiuu. 

 Where the bacilli are much elongated we have true 

 threads, or where several bacilli are arranged in a longi- 

 tudinal direction so-called pseudo-threads ; this thread 

 form is sometimes termed leptothrix. The threads and 

 pseudo-threads never show true branches like the hyphae 

 of the mould fungi ; at the most pseudo-branches are 

 formed by the peculiar apposition of several threads 

 (fig. 31, I). In many forms the bacilli or threads are 

 regularly wavy or corkscrew in form, and these represent 

 the vegetative form termed spirillum or spirocli&te. If 

 the turns of the corkscrew are not markedly developed, 

 and if the spirilla appear more elongated, the organism is 

 termed vibrio. Loops of threads, the ends of which are 

 wound around each other like a plait of hair, are 

 termed spirulina. 



Another form which the fission fungi not uncommonly 

 assume is that of spores. These are spherical or oval 

 cells which serve only for the diffusion and the main- 

 tenance of the species, and always sprout and form again 

 organisms similar to the mother forms from which they 

 arose. 



Further, the fission fungi when grown in exhausted 

 soil and under various other conditions present all sorts 



