SYMBIOSIS 19 



Thus we have, indeed, the antithesis indicated by Tennyson 



Evolution ever climbing after some ideal good 



And Reversion ever dragging Evolution in the mud. 



The constant danger of excess and of reversions from good 

 habits painfully attained indeed has not been left altogether 

 unprovided for by careful Mother Nature. This entailed 

 eventually a multiplicity of safeguarding contrivances, as we 

 actually find them in the physiological economy of both plant 

 and animal. We may thus assume that in the normal course 

 of evolution the plant-animal partners grew with their greater 

 purposes, as a man grows, according to Schiller, " mit seinen 

 groesseren Zwecken." The physiologist would say that struc- 

 ture becomes increasingly modified with reference to the larger 

 functions to be discharged. 



To represent such avowed physiological (and, as I have 

 shown, bio-economic) complements as if they existed only for 

 purposes of their own (" Selbst-Zwecke "), and to slur over 

 their vitally important (symbiotic) food-relation with cheap and 

 frivolous aphorisms seems hardly worthy of an eminent scientist. 



Muesset im Naturbetrachten 



Immer eins wie alles achten. 



For various reasons, which it would take too long to detail 

 here, Prof. Keeble is driven to conceive of C. roscoffensis as an 

 animal which lives like a plant; in other words, as a plant- 

 animal, and that the green cells which form such a prominent 

 tissue in its body possess the same secrets of manufacture and 

 of photosynthesis as those possessed by green plants. 



" A similar apparent total abstinence," he says further, 

 "has been recorded in cases of other animals which contain 

 green or yellow cells not unlike those which occur in our plant- 

 animals. Thus no food has been seen in the bodies of certain 

 adult Radiolaria, Ciliata, Hydrocorallines and Madreporaria, 

 and in all these animals from which remains of food are 

 absent, coloured cells are present. Hence the natural inference 

 has been drawn that such animals subsist on the food-materials 

 manufactured synthetically by their green or yellow cells." 



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