f 



OF fr 



Philosophy of Blicrobes. 27 



life and by the thickness and resistance of their en- 

 veloping membrane. They are generally larger than 

 the spores begotten by endosporulation and resemble 

 cysts. It is this distinction in the mode of formation 

 of spores which serves as the fundamental basis of 

 the classification of Guiguard which we will reproduce 

 later. 



It is not without interest to have an idea of the 

 power of multiplication possessed by these micro- 

 organisms. If we regard a bacterium as dividing 

 itself into two after one hour, we will have four of 

 them in two hours, and in twenty-four hours, 16,000,- 

 000. After forty-eight hours we will have the fabu- 

 lous number of 280 trillions. We can estimate from 

 this the ravages that germs introduced into the blood 

 must produce when they find there conditions favor- 

 able to their pullulation. 



VI. Action of the media upon microbes. 



The medium has necessarily a great influence upon 

 microbes. Besides supplying them with food it is 

 capable of modifying their vitality in different de- 

 grees. 



Certain agents or conditions have the power of 

 bringing bacteria to the condition of latent life, of 

 changing their usual mode of activity, or even of de- 

 stroying them. These agents or conditions are of a 

 nature either mechanical, physical, chemical, or phys- 

 iological. 



1. Mechanical influences. — These are badly deter- 

 mined ; some authors claim to have observed that 

 oscillations impressed upon cultures of microbes are 



