MALADIE ET SYMBIOSE 243 



the fungus appears to be to supply materials in. forms which the 

 usual root-hairs of the orchid are incapable of providing ; in 

 return the latter supports the fungus at slight expense from its 

 abundant stores of reserve materials. The writer on Fungi 

 in the Encyclopaedia Britannica declares such Symbiosis to 

 be a " dualism " where, as in the case of the lichen, " the one 

 constituent (alga) supplies carbohydrates and the other (fungus) 

 ensures the supply of mineral matters, shade and moisture," 

 and, evidently, some fungi at least draw as cross-feeders upon 

 mineral matter. Although this writer is evidently thinking 

 of a good case of Symbiosis, he is yet prejudiced by the usual 

 uncertainties with regard to the determining socio-physiological 

 factors constituting Symbiosis. He does not know how to 

 discriminate, in other words, between good and comparatively 

 bad (trivial) kinds of Symbiosis. But if we fail to realise that 

 there are gradations in " partnerships," and if we mix up 

 promiscuously gocd with bad cases, we are apt to arrive at an 

 inadequate appreciation of Symbiosis, which is at the same 

 time a slander upon Nature. How then are we to assess the 

 value of orchid-cw-fungus Symbiosis ? 



If we had none but orthodox criteria to go upon, we should 

 no doubt say that such a plant-cww-plant Symbiosis is of the 

 same significance as an animal-cww -plant Symbiosis. In . the 

 latter Symbiosis, we might say, the animal merely takes the 

 place of the colourless cells referred to above, and the fungi do the 

 same vis-d-vis to the orchids. Such a view of the matter would 

 be encouraged by the common fallacy that " symbionts," be they 

 animals or plants, only wish to " devour " each other without 

 any provocation. The fungus, so the argument would run, is 

 only another typical Cain, or at best a would-be Cain, such as 

 is the animal. But we cannot any longer rest content with 

 such crude and disingenuous views. We must seek to gain a 

 wider perspective. A partnership, however expedient for local 

 purposes, if it run counter to the great economic scheme of Nature, 

 .g., in matters of respiration, detracts pro tanto from another, 

 more fundamental and essential kind of partnership, namely, 

 that which is in harmony with the great economy of Nature : 

 the ordinary animal-am-plant Symbiosis. I would therefore 

 distinguish between a " Norm-Symbiosis " all-essential and 

 widely and variously useful and a mere " Luxury-Symbiosis " 

 representing by comparison a " lazy compliance with low 



