Microbes in the Static Condition. 13 



Vibrio : microbes spiral, short, (10) ; 



Spirillum : microbes spiral, long and rigid, (11) ; 



Spirochete: microbes spiral, long and flexible, (12). 



2. Forms of involution, of degeneration. — Under spe- 

 cial conditions unfavorable to their nutrition bacteria 

 may assume abnormal aspects, such as swelling in the 

 form of a club, at which place the protoplasm becomes 

 clearer : these special forms are called forms of invo- 

 lution, (14). They have been established in the acti- 

 nomyces, the bacillus of Koch, etc. 



3. Polymorphism. — Microbes are essentially poly- 

 morphic. Recent researches have shown that the 

 same microbe may assume very ditFerent aspects, ac- 

 cording to the medium in which it lives. Thus, the 

 germ of the pyocyanic disease presents itself succes- 

 sively as a bacillus, a spirillum, and a micrococcus. 

 The bacillus of Pasteur's septicemia grows in long 

 filaments in the blood, in short bacilli in the subcu- 

 taneous cellular tissue. The bacillus of symptomatic 

 charbon, cultivated in bouillon containing glycerin 

 and sulfate of iron, takes the form of a clove. With 

 the same germ, therefore, we can obtain several mor- 

 phologically distinct individualities. 



The dimensions of microbes are as variable as their 

 form ; in all cases these are expressed by a few thou- 

 sandths or even fractions of the thousandth of a milli- 

 meter.* 



* [The dimensions of microscopic objects are usually expressed 

 in Microns. A micron is the one thousandth part of a millimeter, 

 and is designated by the Greek letter jW. The dimensions of 

 microbes, expressed in the original of this work in decimal frac- 

 tions of a millimeter, have been rendered in the translation as 

 microns. Thus 0mm., 005=-5/i. — D.] 



