THE ORIGIN OF MICROBES 107 



essential attributes that indicate the infectious 

 nature of the pathogenic microbe, viz., its vaccinal 

 property. Besides, Chauveau has further shown 

 that the non-virulent Bacillus anthracis may be 

 revivified by degrees when grown in suitable media. 

 These researches do not point to any transformation 

 of Bacillus anthracis into a non-pathogenic species, 

 but simply show that oxygen under pressure is 

 capable of modifying the microbe's pathogenic 

 power. In fact, microbes have the power of adapt- 

 ing themselves to considerable variation of external 

 conditions; but this does not involve permanent 

 change in the organism. 



Microbes belong to the vegetal kingdom ; in other 

 words, they are fungi. As they multiply by re- 

 peated subdivision, and also frequently reproduce 

 themselves by spores, which are formed endogen- 

 ously, they are grouped together in a class called 

 the Schizomycetes, splitting fungi, or Spaltpilze, as 

 the German naturalists term them. 



The forms of microbian cells vary considerably 

 they are round, ovate, elliptical, cylindrical, etc. 

 Microbes live isolated, singly, or in larger or smaller 

 colonies, or, in many cases, united in pairs, or many 

 together in threads or groups. Nearly all microbes 

 possess two different modes of life : one of motion 

 and another of rest. In certain conditions they are 

 extremely motile, and when they swarm in a drop 

 of water or other fluid they move among each other 

 in all directions; sometimes rotating round their 

 longitudinal axis, while in other cases the move- 

 ment is an oscillating one, or the threads alternately 



