20 Dr. H. A. Cummins — A Theory of Vegetable Antitoxins. [Jan. 



important bearing on the production and growth of plants, but their 

 influence does not satisfactorily account for many of the facts mentioned 

 in this paper. 



Antitoxins were obtained by Ehrlich of Berlin with some poisons 

 not of bacterial origin but derived from the vegetable kingdom. (Pre- 

 sidential Address, British Association, 1896.) 



General Conclusions. 

 So far as I know a satisfactory explanation has never been given 

 as to the origin or use in the plant of the majority of substances, chiefly 

 of a toxic nature, produced as the result of the secondary processes of 

 metastasis. That these poisons are lethal to the orgaaisms in the soil 

 and primarily produced by their irritation of the plant by entering it 

 and causing fermentation, seems to me a simple explanation. I have 

 mentioned how colouring matters may gain admission to the plant's 

 vascular system, also that the cells exercised an absorptive or destructive 

 influence in the case of the colouring matter absorbed by hyacinths. 

 I have also mentioned the symbiosis which takes place between certain 

 Fungi and the roots of green-ieaved plants : from analogy we may con- 

 clude that there may be a similar relation between bacteria and the 

 roots favourable or otherwise to the plants concerned. The possibility 

 of entrance by the stomata has also been mentioned. We compared the 

 fermentive processes of metastasis in plants and animals, and we saw 

 that the protoplasm in each case acted similarly, so we may infer that 

 under favourable conditions antitoxins may be formed in plants as in 

 animals by any matter capable of stimulating the cells in the required 

 manner. 



The production of many antiseptic substances which we find in 

 plants leads me to believe that they are produced in most cases as the 

 result of irritation of the cells of the higher plant by the entrance of 

 organisms causing fermentation of the juices of the plant. 



That organisms could have every opportunity of doing so unchecked, 

 and of multiplying in deciduous trees is evident, as the sap lies for a long 

 time in the cells and vessels waiting for the young buds to develop and 

 open. If it were not for a substance which could be supplied by the 

 cells to neutralize the effect of, or kill the fermentative organisms, the 

 plant must die. 



In plants belonging to the Natural Orders Apocynacese, Euphor- 

 hiaceas, &c., the white milky nutrient juice generally possesses an acrid 

 or poisonous principle evidently to protect it against fermentation. 



That every facility is given to protophytes to approach the roots oi 



