THE NEW FERTILIZATION. 99 



winged creatures ; white men, yellow men, black men ; giants 

 and dwarfs ; civilized men and savages ; elephants, monkeys 

 and mice ; vultures, pheasants and flies with all the various 

 kinds of foods consumed by these different creatures, and all 

 the different avocations, industries and modes of life which 

 are found amongst them, we would find an equal, and perhaps 

 in some respects a greater, difference existing among the mi- 

 nute objects of our study. 



Bacteria vary in size from one twenty-five hundredth to one 

 twenty-five thousandth of an inch in diameter, so that a great 

 swarm of them might dwell within a single drop of water. In 

 shape they are spherical, oblong, rod-like, straight, curved and 

 spiral. They multiply by division; a part of the body pro- 

 trudes and is cut off by a constriction of the mass, forming 

 a second body, fully developed like the parent, both of which 

 then proceed to repeat the process, thus increasing numbers 

 with prodigious rapidity. A very small colony of bacteria 

 placed in a hogshead of water properly prepared will, within 

 a few hours, discolor the whole content with their presence. 



A temperature of 130 degrees Fahr. causes bacteria to cease 

 all activity, and at a somewhat higher temperature many of 

 them are rendered inert forever. They are most active be- 

 tween 75 and 100 degrees, and this, as we shall see, is why 

 plants make their most vigorous growth during the Summer, 

 and why the Tropics are more prolific in vegetation than the 

 other zones. 



Though most active at nearly 100 degrees Fahr., they with- 

 stand extremes of cold better than extremes of heat. Freez- 

 ing suspends their life, but does not destroy it. They have 

 been found upon the bare rock of high mountains where the 

 temperature never rises above freezing, and being brought 



