WHAT PEOPLE ARE MADE OE 
43 
rest of the protoplasm also divides, half going round one 
piece of the nucleus, and half round the other.” 
Tiny one-celled creatures like those that make up the 
sea-dust multiply almost too rapidly for our imagina¬ 
tion to follow. One of them may become a million in a 
week, and a quarter million can lie in a gallon of water. 
In one square yard of lake water there may be, at the 
height of the breeding season, 7,000 million of them. 
Perhaps it is just as well that the next largest creatures 
devour them before they become so many as to choke up 
the lakes and rivers and seas! 
A hundred years ago, when now and again people dis¬ 
covered a new cell, different from all cells they had ever 
seen, they used to think that this cell came into being all 
by itself, that it was its own father and mother and 
grandfather and grandmother. In those days, micro¬ 
scope makers had not learned to make fine lenses such as 
we have to-day, and it takes a very powerful lense to 
find out the truth! So men thought a new cell could 
appear right out of the air, without having any par¬ 
ents at all. Patient men had to spend their lives look¬ 
ing into the microscope to prove that this is not so. No 
cell appears by itself; every cell was once a part of some 
other cell, and became an independent cell only when the 
parent cell divided. An animal is just a great big col¬ 
lection of cells, and you never heard of an animal ap- 
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