l886.] NEW-YORK MICROSCOPICAL SOCIETY. 121 



destroyed human life. The disease called tuberculosis is sup- 

 posed to be caused by a bacterial organism, which enters the 

 lungs, multiplies, and occasions the wasting called consumption. 

 The fact that bacteria have been found connected with some 

 forms of disease would apparently indicate that those diseases 

 are of bacterial origin, although it has not yet been fully determ- 

 ined whether the bacteria may not be merely the accompani- 

 ments of such diseases. Inoculation with the bacteria which 

 are supposed to be the cause of a certain disease would seem 

 to offer means for determining this question, but even this 

 method of experiment is beset with difficulties. If, for ex- 

 ample, a man were inoculated with the bacterium of, say, ty- 

 phoid fever, satisfactory information might be the result. But 

 men are not available for such purposes ; hence, resort is had 

 to the inferior animals, some of which are not susceptible to the 

 diseases of man. Definite results, therefore, are as yet unobtain- 

 able ; although Pasteur's experiments with splenic fever dem- 

 onstrate, apparently, the truth that vaccination with the Bacillus 

 anthracis, whose virulence has been weakened by successive 

 cultivations, affords protection to certain animals from splenic 

 fever. The hope is entertained that many kinds of disease may 

 yet be avoided by means similar to those employed by Pasteur 

 in the case just cited. 



There are different theories as to the way in which vaccina- 

 tion protects. One is, that when a crop of bacteria enters the 

 system they consume all the food necessary for their support 

 which the system contains, leaving none for a second crop. 

 Another is, that the bacteria introduced generate not only the 

 poison which causes the illness for which they are introduced, 

 but also a poison destructive of themselves. But, in my opin- 

 ion, the theory generally accepted is, that the blood contains 

 that which kills the bacteria. A curious feature of tuberculosis 

 is, that a dweller in cities, say New York, affected with it, on 

 removing to certain parts of the country, the Adirondack moun- 

 tains, for example, can, by proper exercise and diet, practically 

 recover from his ailment, although the bacteria which are sup- 

 posed to cause that ailment may be present in his system all the 

 time. But on his returning to his city home the disease re- 

 sumes its ravages. This would indicate that the mountain air 

 and the conditions under which the sick man lived in such air, so 



