242 SYMBIOSIS 



to a cul-de-sac of evolution. Most fungi resemble the colourless 

 cells of higher plants in their nutrition. Like them, they require 

 water, small but indispensable quantities of salts of Potassium, 

 Magnesium, Sulphur, and Phosphorus, and supplies of carbo- 

 naceous and nitrogenous matters in varying stages of complexity 

 in the different cases. Like them also, they respire oxygen, 

 and are independent of light ; and the several powers of growth, 

 secretion and general metabolism, irritability and response to 

 external factors, show similar specific variations in both cases. 

 " Free-lances," or " Free-booters," though they be, the fungi 

 are thus by their needs dependent upon green plants dead or 

 alive. And there is clearly some opportunity for the fungi, by 

 being in turn useful to the green plants, reverting to the 

 symbiotic usefulness of the colourless cells in an ordinary higher 

 plant to rehabilitate themselves to some extent as useful 

 bio-ecomonic agents, and, though not, as autonomous beings, 

 re-exalted in the evolutionary scale (which would be contrary 

 to the " law of loss " or " irreversibility,") yet strengthened in 

 their general powers for good, and even elevated through union, 

 as is clearly instanced by the case of the lichen. De totde taille 

 bon c.hien. Large numbers of fungi, of course, are well known to 

 gain their living exclusively by parasitic short-cuts. If others 

 occasionally submit to Symbiosis,they are not yet quite degenerate 

 and do so under a special compulsion, making a virtue of necessity, 

 e.g., when other means of gaining a livelihood are wanting, 

 or when they are occasionally made to yield to the pressure of 

 symbiotic momenta in the shape of prepotent " good influences " 

 wielded by higher plants. The ancestors of the fungi, be it 

 remembered, were green plants, and, hence, were undoubtedly 

 possessed of some symbiotic disposition. We may take it that 

 even in degeneration the symbiotic sense is frequently not 

 entirely defunct, but only in abeyance and capable of some 

 reawakening on appropriate occasions ; and 1 believe that this 

 applies in the case of both fungi and orchids. Even in highly 

 saprophytic orchids there occurs not infrequently a reappearance 

 of green cells, and we may confidently believe that similarly there 

 exist residues rudiments of an erstwhile more developed 

 symbiotic sense even amongst the lower classes of plants, such 

 as the fungi, some of which may be but little inclined to be 

 saprophytic. 



In case of Symbiosis between orchids and fungi, the role of 



