20 
IOWA ACADEMY OF SCIENCES. 
Micro-biology extends her aegis also over the herds and 
crops of man. She destroys the insect enemies of our 
grain fields and protects vine and fruit tree from blight 
and mildew. She saves the silk worms of Europe from 
the plague which threatened their destruction, and the 
flocks and herds of America from some of their most 
destructive diseases. In twelve years the application of 
Pasteur’s inoculations saved France seven million francs 
in the item of anthrax, and reduced the mortality of hog 
erysipelas from 20 per cent to 1.45 per cent. 
Thus science performs a service to society incalculable 
in its value. It defends it from foes, both within and 
without the gates. It prolongs life, assuages pain, lessens 
disease, and makes death a euthanasy. So notable have 
been its victories during the century that we may almost 
prophesy the speedy coming of the time when the only 
deadly bacillus remaining will be that as yet undescribed 
species of bacillus senectutis, or at least when only suffi- 
cient of disease will be left on earth to provide for the 
speedy and a beneficent extirpation of the unfit. 
Viewing organic evolution from the angle of the physi- 
cist and considering the animal body simply as a machine 
for the transformation of potential into kinetic energy, the 
secular process sums itself up in the production of better 
and better machines. From the fish of the early Paleozoic 
on to the amphibian of the Carboniferous, the reptile of 
the Mesozoic, and the mammals of the Tertiary and of the 
present, we have a series of higher and higher organisms, 
each capable of doing more work and better work than its 
predecessors. 
It is possible to construe social evolution in the same 
terms. Primitive society was weak. The energy at its 
disposal was that only of the human body, the beast of 
burden, and to a limited extent, of wind, water and flame. 
So feeble was the ancient state in what may be termed its 
musculature, so little could it utilize the forces of nature, 
that it may be compared with a stage of organic evolution 
preceding that of the vertebrata, that, let us sa}^, of the 
