GENERAL CHARACTERS OF BACTERIA r5 
much smaller number of species. Itis frequently uncertain whether 
aspecies described by one bacteriologist is the sameas that de- 
scribed by another under the same name. The difficulties in the 
way of a proper description and classification of the species of 
bacteria have hitherto been insurmountable, and at the present 
time the subject is in such extreme confusion that no one except an 
expert can understand it. Fortunately this confusion of species 
is of no Importance for our purpose. Agricultural bacteriology is 
not at present concerned with the problem of the species. All that 
it is necessary for us to know in connection with our subject will be 
referred to in the separate sections in the following pages, and the 
subject of the classification of bacteria may be left without further 
consideration. 
Multiplication of Bacteria—As already mentioned, the 
primary method of the multiplication of bacteria is by simple 
division. Bacteria are so minute that it seems strange to assign 
to them much of a part to play in nature’s processes. But their 
extraordinary power of multiplication gives them unlimited possi- 
bilities. 
The elongation of a rod and its division into two parts, followed 
by a repetition of the process, may be extremely rapid. Fre- 
quently it does not take more than half an hour for the whole 
phenomenon to take place, and sometimes even less time is re- 
quired. Such division, in geometrical ratio, results in an increase 
in numbers that is almost inconceivably great. Ifa division once 
an hour could be maintained for twenty-four hours, there would be 
produced, as the offspring of a single bacterlum, some seventeen 
million descendants, and in five days there would be a mass suff- 
cient to fill the oceans. This rate is, manifestly, not continued for 
any great length of time, or the world would be full of them; their 
growth is checked by lack of food, and still more by the substances 
they secrete, which act as poisons. But this possibility of repro- 
duction represents an almost unlimited power, constantly curbed 
by the lack of proper conditions. Bacteria may thus be looked 
