32 
Apart from these considerations, there was another law which 
seemed to run through plants and animals, viz., the provision made to 
keep down, or within limits, all tribes of plants and animals, so as to 
prevent, as it were, an extinction of some families or species through 
the overrunning of others. 
There would be little difficulty in showing that, as far as the 
geological record revealed the facts, vast tribes of plants and animals 
had disappeared, to make way, it might almost be said, for higher and 
more developed forms, and, whether we accepted the conclusions of 
the evolutionists or not, the mass of life now was decidedly in advance 
of that of any other period of geologic time which preceded the exist- 
ing Fauna or Flora. Of this it would be scarcely necessary to give 
examples, because to the most cursory observers the facts were patent. 
If it were considered for one moment what would be the condition 
of things, if there were not agencies at work to keep down both plants 
and animals, we should possibly be startled by the calculations. Take 
for instance any one of our forest trees, which, like the sycamore, beech, 
or the oak, matured their tens of thousands of seeds annually—if there 
was nothing to keep them down, the land would in a few years be 
overgrown with these trees alone. Descending to smaller and less 
conspicuous plants, such as the groundsell, the shepherd’s purse, or 
the chickweed, which seemed to produce several crops a-year,—in the 
course of but a few years, were there not some provision to check their 
progress, the whole land would be covered by them. 
Take, among the animal creation, those pests to the gardener, the 
Aphis tribe. If the calculations be correct, one Aphis producing only 
50 individuals for the first brood in the spring might be the fertile 
cause of so many individuals by autumn, that packed closely together 
her progeny would cover ten acres. Or assuming that the roe of a 
single codfish developed as many fish as there were ova, and so on for 
a few generations, but a short time would elapse before the sea would 
be full of codfish alone. Seeing these things did not occur, it might 
naturally be asked what agencies are at work to prevent such a 
catastrophe. 
Both with animals and plants one agency by which they were kept 
down was this, they served as food to other animals, and when we 
sometimes unthinkingly asked what was the use of such and such 
