Page:Popular Science Monthly Volume 38.djvu/398

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384
THE POPULAR SCIENCE MONTHLY.

White mice are safe against it. This circumstance of late occasioned R. Koch to ascertain, by experiments, whether predisposition to glanders might not be artificially induced by changing the composition of the animal juices. The change consisted in the formation of sugar in the blood of the mice, which received as food phloridzin, a crystalline compound, naturally preformed in the roots of fruit trees and easily splitting up into sugar and some other products. It undergoes a similar change when brought into the circulation of the blood. The result of these experiments was, that white mice lose their immunity and become susceptible to glanders when phloridzin is given to them; infection by this disease invariably took place when the mice were inoculated to the virus, and thus the proof was furnished that by changing the chemical conditions of an animal its immunity from infectious disease may be neutralized. This indicates that immunity in the present case, as in the action of carbon monoxide, depends upon the composition of the blood, predisposition being established when the composition is changed.

These facts indicate that, as to susceptibility to and immunity from the effect of poisonous and virulent matter, the composition of blood is of the highest signification, and that the changes caused chiefly relate to its condition. They coincide with the experience that the action of poisons throughout is quickest and most energetic when they are injected into the blood; moreover, there seem to be many substances existing which induce infection only when present in the circulation of the blood, but not when brought into the digestive channel. Apparently harmless lesions can turn out disastrously, when even the smallest trace of a virus happens to reach the wound.


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THE DECLINE OF RURAL NEW ENGLAND.

By Prof. AMOS N. CURRIER.

IN every period of American history the influence of New England has been marked and out of proportion to its size and population. In religious thought and activities, in great moral and social movements, in literature and scholarship, in inventive genius and the skilled industries, in the pulpit, at the bar, on the bench, and in legislative halls, New-Englanders have always stood in the front rank and have contributed largely to the worthiest American achievements.

Now, the bulk of this population, until very recent years, has been rural rather than urban, and the towns themselves, large and small, have been made up of the country-born and country-bred, while almost the entire stream of emigration that has