384 THE POPULAR SCIENCE MONTHLY. 



White mice are safe against it. This circumstance of late occa- 

 sioned R. Koch to ascertain, by experiments, whether predispo- 

 sition 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 ener- 

 getic 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. 



-*-*- 



THE DECLINE OF RURAL NEW ENGLAND. 



By Teof. AMOS N. CUKKIEE. 



IN every period of American history the influence of New Eng- 

 land 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 



