SILOS, ENSILAGE AND SILAGE. 59 



They multiply by fission, each individual " dividing 

 into two similar daughter cells through an unlimited 

 number of generations." 



Keproduction by spores has been observed in many 

 species, and it is probable that this process is common 

 to all. To this group belong various specific ferments, 

 as the lactic, acetic, butyric, etc., and a number of 

 forms that produce putrefaction. They are all micro- 

 scopic forms, many of them less than 25000 of an inch in 

 diameter, and they are, at present, classified from pecul- 

 iarities of form.* 



The conditions of temperature, moisture and food 

 supply, as already noticed, have a marked influence on 

 the vital activities of bacteria, and they will, to a con- 

 siderable extent, determine the successful reproduction 

 and growth of a particular species, to the exclusion, for 

 the time, of other less favored species. In the struggle 

 for existence, the individuals that are best adapted to 

 the sum of the conditions in which they are placed, will 

 have many advantages over their competitors, and this 

 will enable them to take the lead in appropriating the 

 materials required in their processes of nutrition, and 

 thus become masters of the situation. 



Any change in the surrounding conditions that places 

 this favored form at a disadvantage, will tend to check 

 its activities, and bring to the front some other form 

 that is better adapted to the new conditions. The 

 normal activities of a dominant form may prepare the 

 way for its own suppression and favor the aggressions of 

 its rivals. An exhaustion, or even scarcity, of its appro- 

 priate food supply, or the form in which the food is 

 furnished, or an accumulation of residues resulting from 



* The globular forms are called Cocci, the smaller ones Micrococci, and the 

 larger Macrococci. When grouped in pairs they are Diplococci, and when in 

 chains or rows Streptococci. The rod-like forms, if short, have been called Bac- 

 teria, and the longer rods Bacilli. Spirally curved forms are Spirilla, Spirochsetse, 

 or Vibrios. 



