1 6 BACTERIA 



the body protoplasm. Migula holds the former view, and 

 states that the position of flagella is constant enough for 

 diagnostic purposes. They are but rarely recognisable 

 except by means of special staining methods. Micrococcus 

 agilis (Ali-Cohen) is the only coccus which has flagella and 

 active motion. 



Modes of Reproduction, Budding, division, and spore form- 

 ation are the three chief ways in which Schizomycetes and 

 Saccharomycetes (yeasts) reproduce their kind. Budding 

 occurs in some kinds of yeast, and would be classified by 

 some authorities under spore formation, but in practice it is 

 so obviously a " budding " that it may be so classified. The 

 capsule of a large or mother cell shows a slight protrusion 

 outwards which is gradually enlarged into a daughter yeast 

 and later on becomes constricted at the neck. Eventually 

 it separates as an individual. The protoplasm of spores of 

 yeasts differs, as Hansen has pointed out, according to their 

 conditions of culture. 



Division^ or fission, is the commonest method of repro- 

 duction. It occurs transversely. A small indentation occurs 

 in the capsule, which appears to make its way slowly 

 through the whole body of the bacillus or micrococcus until 

 the two parts are separate, and each contained in its own 

 capsule. It has been pointed out already that in the incom- 

 plete division of micrococci we observe a stage precisely 

 similar to a diplococcus. So also in the division of bacilli 

 an appearance occurs described as a diplobacillus. 



Simple fission requires but a short period of time to be 

 complete. Hence multiplication is very rapid, for within 

 half an hour a new adult individual can be produced. It 

 has been estimated that at this rate one bacillus will in 

 twenty-four hours produce 17,000,000 similar individuals; 

 or, expressed in another way, Cohn calculated that in three 

 days, under favourable circumstances, this rate of increase 

 would form a mass of living organisms weighing 7300 tons, 



