‘TIME AND CHANGE 
perience in organization, at last made the problem 
of the origin of man easier to solve? 
One fancies every living thing as not only re- 
turning its mineral elements to the soil, but as in 
some subtle way leaving its vital forces also, and 
thus contributing to the impalpable, invisible store- 
house of vital energy of the globe. 
At first among the mammalian tribes there was 
much muscle and little brains. But in the middle 
Tertiary the mammal brain began suddenly to en- 
large, so that in our time the brain of the horse is 
more than eight times the size of the brain of his 
progenitor, the dinoceras of Eocene times. 
Nature seems to have experimented with brains 
and nerve ganglia, as she has with so many other 
things. The huge reptilian creatures of Mesozoic 
time — the various dinosaurs — had ridiculously 
small heads and brains, but they had what might 
be called supplementary brains well toward the 
other end of the body, — great nervous masses near 
the sacrum, many times the size of the ostensible 
brain, which no doubt performed certain brain func- 
tions. But the principle of centralization was at 
work, and when in later time we reach the higher 
mammalian forms, we find these outlying nervous 
masses called in, so to speak, and concentrated in 
the head. 
Nature has tried the big, the gigantic, over and 
over, and then abandoned it. In Carboniferous 
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