MANNER OF ACTION. 137 



passed away from the medical profession forever. A few men 

 may take these things on faith, and wait for time to develop 

 the rational answer, but the many will wait, and watch for 

 farther developments to point out a reasonable and philosophic 

 answer, before they will accept this theory without reserve. 

 Can such an answer be given with our present knowledge of 

 the subject? If it be required that every step be proven by 

 actual demonstrated fact; if reasonable circumstantial evi- 

 dence be not admitted, only a few cases can be clearly made 

 out. But on the other hand, if the physiology, as previously 

 explained, be accepted, the manner of the production of dis- 

 ease becomes clear. I should not insist that the poisonous 

 substance must, in every case, be an alkaloid. But it must 

 be an organic compound closely akin to an alkaloid. To say 

 that these organisms produce disease, simply by their presence, 

 is not a sufficient explanation. We all know that their pres- 

 ence is not, in itself, a sufficient cause; for if this were so, one 

 organism would be as potent as another. And we all know, 

 who have had any experience in the examination of these 

 forms, that many of them are without any evil effect what- 

 ever; that wounds in the mouth and elsewhere heal readily 

 and perfectly when covered with them. We also know that 

 the great majority of the higher plants are innocent of any 

 evil effect upon the human system; and it is perfectly reason- 

 able that we should find the same differences to exist among 

 the lower plants. Many kinds of plants grow together with- 

 out injury to each other; but plants are found that destroy 

 their neighbors by the poisonous effects of their waste pro- 

 ducts. Then it seems plain that the differences must be found 

 in the peculiar products to which the particular organism gives 

 rise. These we have already sufficiently explained. We have, 

 also, sufficiently explained the modus operandi, in the de- 

 struction of organic substances in general. They are simply 



