BIONOMICS 235 



of the electric discharges, is also, I believe, of peculiar 

 significance with reference to my generalisation that nature 

 abhors perpetual in-feeding; because antagonistic to the law of 

 symbiogenesis. 



That the peculiar relation between particular substances, 

 especially plant substances, and particular parts of the animal 

 nervous system, are of evolutionary origin and evolutionary 

 significance, can now no longer be doubted. It is futile to 

 treat the oft-times appalling potency of the plant alkaloids on 

 animal physiology as a mere local matter. These alkaloids, in 

 my view, are the expression of a deep-seated antagonism of 

 the plant world to animal depredation. C. Simmonds points 

 out the following in Nature (21/8/13) : 



The alkaloids of plants have long offered a most interesting and 

 attractive, if always difficult, field of research to both chemists and 

 physiologists. The subtle chemistry of the vegetable cell evolves no 

 objects more fascinating to study than these "vegetable alkalis" as 

 Serturner first termed them. 



When, however, the chemical structure of an alkaloid has been 

 elucidated, there yet remains a problem of great general importance, 

 namely, how its chemical constitution is correlated with its action on 

 the animal system. What is the deft arrangement of atoms which 

 confers upon strychnine its tetanising action, convulsing all the muscles 

 of the body ; and what, on the other hand, is the arrangement in 

 curare, a drug which paralyses the motor nerve endings without affecting 

 the excitability of muscle? Many useful observations have been made 

 on this question, but the difficulties are great, and progress slow. A 

 comparatively simple case is quoted where two investigators, after 

 studying the relation between the mydriatic action and the chemical 

 constitution of the tropeines, were forced to the conclusion that no 

 generalisation could be made which would explain all the results they 

 obtained. 



Another question which has been much debated is the mode of 

 formation of the alkaloids in the plants. The view mostly favoured is 

 that they, or at least some of them, are decomposition-products of 

 proteins, chlorophyll, and other complex substances. As regards their 

 function in the plants, they have been variously considered as nutrient 

 materials, protective substances, or end-products of metabolism, rendered 

 harmless to the plant and stored chiefly in special cells whence they are 

 not readily re-absorbed into the active plant tissues. 



