TAXONOMY 
223 
Form of Cell Groups after Cleavage. —The individual bacteria 
after cleavage may separate, or cohere. The amount of cohesion, 
together with the plane of cleavage, determines the various forms 
of the cell groups. Thus, among the cocci, diplo- or double forms 
may result giving rise to distinguishing morphological character¬ 
istics. Similarly among the bacilli characteristic forms result 
as single individuals and others which form chains of various 
lengths. 
Rapidity of Growth and Multiplication. —The rapidity with which 
bacteria grow and multiply is dependent upon species and environ¬ 
ment. The rapidity of the growth is surprising. Under favorable 
conditions they may elongate and divide every twenty or thirty 
minutes. If they should continue to reproduce at this rate for 
twenty-four hours a single individual would have 17 million de¬ 
scendants. If each of these should continue to grow at the same 
rate, each would have in twenty-four hours more, 17 million off¬ 
spring, and then the numbers would develop beyond conception. 
However, such multiplication is not possible under natural or even 
artificial conditions, both on account of lack of nutritive material 
and because of the inhibition of the growth of the bacteria by their 
own products. If they did multiply at this rate in a few days there 
would be no room in the world but bacteria. 
Chemical Composition of Bacteria. —The quantitative chemical 
composition of bacteria is subject to wide variations, dependent 
upon the nutritive materials furnished them. About 80 to 85 
per cent, of the bacterial body is water; proteid substances constitute 
about 50 to 80 per cent, of the dry residue. When these are ex¬ 
tracted, there remain fats, in some cases wax, in some bacteria 
traces of cellulose appear, and the remainder consists of 1 to 2 per 
cent. ash. 
The proteids consist partly of nucleo-proteids, globulins, and 
protein substances differing materially from ordinary proteids. 
Toxic substances known as endotoxins to distinguish them from 
bacterial poisons secreted by certain bacteria during the process of 
growth, also occur. 
