BACTERIA AND THEIR RELATION TO DAIRYING. 5 



been found in air, soil, water, dust; on our clothes, on our 

 skin; in the alimentary canal of man and animals, in our 

 food; on the trees and the flowers, on the smallest as well 

 as the largest animals, in short, in almost every place on 

 earth. Among the few exceptions to the omnipresence of 

 bacteria may be mentioned that they are never found in 

 the uninjured animal and vegetable cells or in fresh, 

 unwounded animal and vegetable organs. Their won- 

 derful general distribution is due largely to their exceed- 

 ingly small weight ; they are easily carried around in the 

 air, and when dry are moved by the least current. Certain 

 bacteria furthermore possess power of locomotion in the 

 fluids adapted to their development, and they can therefore 

 spread in these substrata with wonderful rapidity. 



Multiplication of Bacteria. The main reason of the 

 universal presence of bacteria is, however, not to be found 

 in any of the conditions mentioned, but in their enor- 

 mously rapid reproductive capacity. This takes place 

 partly by division, partly by spores. 



a. Multiplication by Division. Bacteria may divide in 

 different ways. The most common method is by the sim- 

 ple division of a single cell-element into two equal parts 

 (fission). This may continue in a linear direction, giving 

 rise to long threads or chains of cells. In the case of coccus 

 forms the continued division into twos may give rise to 

 the streptococci (chain cocci) ; or, if irregular and in two 

 planes, it may form flattened surfaces or launches pus 

 bacteria. 



If division occurs in three planes we have the formation 

 of the cubical masses or sarcina groups. 



Under favorable conditions the multiplication through 

 division may take place very rapidly. It has been observed 



