218 SYMBIOSIS 



factor the specialisation of the functions of the fore and hind limbs. While 

 the animal reaches about with its fore-limb, the hind-limb becomes the sup- 

 porting organ. With the evolution of this process there comes about a 

 final liberation of the fore-limb from any such servile function as supporting 

 the weight of the body ; it becomes a free organ full of possibilities, and 

 already capable of many things. This process I am terming the emancipa- 

 tion of the fore-limb, and its importance as an evolutionary factor appears 

 to me to be enormous. 



This plausible, if hurried, account of man's evolution, I believe,, 

 on the whole corroborates the view here set forth, namely, that 

 it was fundamentally the search for the vital spare products of 

 the higher plant which prompted the essential emancipation 

 of the fore-limb. When we are made to visualise a " non- 

 specialised " animal, depending little upon " nails and claws,"" 

 we know that we are not far removed from a symbiotic animal. 

 We are introduced to an inoffensive, plastic, yet wisely con- 

 servative creature, exhibiting a well-balanced division of labour 

 and right proportions down to the very details of organisation- 

 the advantages incidental upon symbiotic relations of a high order,, 

 associated, as a matter of course, with non-felonious food-getting. 

 We conclude that it was the ennobling appetite with all it 

 entailed, that ensured the mobility and emancipation of the 

 fore-limb and saved it from " servile function." 



As already noted, numerous Amphibians are characterised by 

 cross-feeding habits. That short-cuts to tree-climbing have never 

 been really successful, recalls the similar ill-success of some 

 Hymenoptera in trying to obtain the nectar by short-cuts, in 

 avoidance of Symbiosis, e.g., by biting holes into the corolla. 



In either case there is required, as the norm of life, an 

 adaptation at once temperate and pregnant in bio-economic, 

 i.e., widely useful, consequences, and this cannot be achieved 

 except by gradual, painstaking and honest specialisation. 



Prof. Wood Jones cautions us against regarding the 

 arboreal habit per se, or even the emancipated fore-limb, as the 

 talisman ; and, from what he says on the subject, it is clear that 

 Carnivorism is not apt to confer the happy mean of adaptation. 

 Thus we learn : 



Other mammalian stocks have taken to an arboreal habit ; but they 

 kave taken to it after varied periods of quadrupedal life. They have taken 

 to it too late to derive the full benefits from it, for they took to it with the 

 fore-limbs already deprived of some of their inherited mobility. Such 

 animals never become perfect tree-climbers. They may acquire an extra- 

 ordinary skill in running about the branches of trees, as many Rodents 



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