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Co*=opecat(on in plante/' 



By Geo. Clayton, F.C.S., of the Northern Col. of Pharmacy. 



THE matter I propose to speak about is symbiosis, also to 

 touch on parasitism, though more with the object of dis- 

 tinguishing between it and symbiosis, and also to give 

 illustrations of pure partnership between one plant and another 

 plant, and also between a plant and an animal. A pure parasite, 

 as most of you will know, is a plant or animal which, living on 

 another plant or animal called its " host," withdraws nutriment 

 from it, without in any way contributing to the support of its host. 

 In the plants yellow-rattle, cow-wheat, etc., we have good examples 

 of plants parasitic on other plants. Here I must mention that 

 parasites must not be confounded with epiphytes or saprophytes. 

 Epiphytes being plants like the orchid, which are attached to other 

 plants, but derive no nutriment from them, getting their nourish- 

 ment from the air by means of their pendulous roots. The 

 saprophytes being plants like the toad-stool, which live on dead or 

 decaying vegetable matters. A true parasite then lives on its 

 living host, having mechanical attachment with it and withdrawing 

 nutriment from it, but giving the host-plant nothing in return. 

 The common yellow rattle, whose yellow flowers are seen in 

 every pasture field, lives on the roots of the clover, and takes 

 its sustenance from it. 



But in a great many cases it is most difficult to decide for 

 certain that the host-plant does not get some advantage from the 

 parasite which drains its juices. Should this be the case, however, 

 the latter would no longer be a parasite, and the relationship 

 between the two would be one of mutual assistance — a partnership 

 for the benefit of both. Until lately, for example, the mistletoe 

 was regarded as a true parasite; but some botanists now state that 

 this plant, the mistletoe, contributes food stuff (starch, cellulose, 

 etc., which it has manufactured in its leaves) to the oak, apple, or 

 poplar tree to which it is attached. These botanists point to the 

 enlargement, corpulence, or general robustness of the apple stem 

 in the particular place where the mistletoe is attached, and argue 



* From the British and Colonial Druggist. 



