26 



PHARMACEUTICAL BACTERIOLOGY. 



and by some is supposed to be a nucleus in a divided state. A nucleus 

 proper does not exist, or, rather, has not been demonstrated. The cyto- 

 plasm, as a rule, stains quite readily.. Distributed through the cytoplasm 

 may be found various substances, elaborated by cytoplasmic activity. 

 Polar granules (metachromes or Babes-Ernest granules) have been observed. 

 Sulphur, fat, pigment, chlorophyll, etc., may be found. 



The cell-walls of many species undergo a gelatinous change. This 

 change may affect the outer layers only, or it may involve the entire thickness 

 of the wall, forming the gelatinous substances noticeable in bacterial cultures 

 and in other substances (stringy cultures, stringy milk, etc.) . This gelatin- 



FIG. 7. General morphology of the Spirillaceae. a, S-shaped or single spiral; b, 

 double spiral; c, multiple spirals; d, slender threads; a and b have fixed bodies, motion 

 being caused by flagellae; c and d, bodies flexible, motion not due to flagellae. 



ous substance also causes the individual organisms to cling to each other, 

 thus causing the formation of the peculiar zooglea masses in natural as well 

 as in artificial culture media. 



The cilia or flagellae are very delicate threads, supposed to extend from 

 the cell-plasm, through the cell-wall, into the surrounding medium. The 

 delicate threads are probably cytoplasmic in nature, and by their rapid 

 vibratory motion enable the microbe to move about within liquid media. 

 Some microbes are apparently without flagellae, nor is it definitely deter- 

 mined that all motile microbes have flagellae. Some authorities are inclined 



