THE VEGETABLE KINGDOM. 



463 



by assuming that the roots emit products favourable to 

 certain species and hurtful to others; products which 

 Plenck, with all the coarseness of one of Moliere's doctors, 

 called the "excrement of plants." 



Duhamel, when having some elms cut down, had 



240. Palmated Blmh&ih— Rheum palmatiim (Linnasus). 



already noticed that the soil in which they had stood had 

 undergone a certain alteration, having become unctuous. 



A Genevese observer, M. Macaire, Avent even further. 

 He observed that when roots of chicory or Euphorbia 

 were placed in water, they exuded into it a coloured 

 extractive mattei", which could only be an excretion. 



59 



