44 Tlie Farmer's Veterinary Adviser. 



of eggs, the result of the action of various bacteria, is equally 

 familiar. Yet Dubois shows that the effect of a strong 

 electric current is fatal to the Micrococcus prodigiosus. 



^a^.ia, another important agency. Each bacterium has 

 a given *|^ge of temperature within which its propagation 

 is most active. All excepting those that have produced 

 spores are destroyed by exposure to a high temperature — 

 from that of boiling water down. Different spores will re- 

 sist boiling for different periods. 



Cold arrests the growth of bacteria, but does not neces- 

 sarily kill them, many i-eviving after prolonged freezing. 

 Plague-generating bacteria that are destroyed by cold pro- 

 duce those plagues which, like cholera, Texas cattle fever, and 

 yellow fever, do not survive the winter in northern latitudes. 

 The possibility of the action of bacteria for evil may be 

 deduced from their power of rapid increase in suitable sur- 

 roundings. They multiply their numbers by fission— one 

 enlarging and dividing into two, and thus some of them 

 can, under favorable conditions, double their numbers every 

 hour. A single bacterium increasing at this rate would, in 

 twenty-four hours, have produced 16,777,216. These, again, 

 multiplying at the same rate would, at the end of twenty- 

 four hours more, amount to 282,584,976,710,656. A single 

 Bacterium tenno (of putrefaction), one-thousandth of a 

 millimeter in diameter and a five-hundredth of a millimeter 

 in length, would produce in forty-eight liours a sufficient 

 progeny to nearly fill a half-pint measure. The increase 

 attained, in five days at the same rate is so enormous that 

 to state it would only arouse incredulity. The curious can 

 calculate it for himself, doubling the product every hour. 



Fortunately for the world the bacteria cannot find such 

 opportunities for unrestricted increase, but they perish in 

 unlimited numbers by starvation, by the action of light, 

 heat, cold, oxygen, electricity, chemical poisons, by the ac- 

 tion of other living organisms, and even by preying on each 



