220 SYMBIOSIS 



Unwittingly, Prof. Wood Jones bears witness to the same 

 truth, as when he says : 



It is a very remarkable fact that in the numerical development of the 

 individual bones which compose the separate fingers, the Chelonians 

 (Tortoises and Turtles) are the match of Man and his nearest mammalian 

 neighbours. There is evidently something extraordinarily primitive 

 about the hand that has been preserved and passed on to Man ; but like 

 the primitive rotating forearm, this primitive, simple and unspecialised 

 five-fingered hand is full of possibilities. 



And again : 



It is a fact which cannot be ignored, that in the details of its skeletal 

 elements, the fore-limb of the highest of the Mammals finds its likeness 

 among living Vertebrates in such a primitive creature as the tortoise. 



The significance of the parallelism, in my opinion, is this, 

 that in either case the early ancestors were characterised by a 

 similar fjw ratio, and that there was a persistence of similar, if 

 not identical, temperate and cross-feeding habits. There is no 

 doubt that the Chelonians are now, and have been in the past, 

 largely cross-feeders. To this day by far the larger numbers are 

 herbivorous or frugivorous, and, like other cross-feeders, they 

 are remarkable for their longevity and retention of life. They 

 can exist for months without eating. The tortoises feed chiefly 

 on leaves, berries and lichens, and many turtles are strictly 

 herbivorous, feeding upon algae and Zostera marina, the edible 

 " Dulce," growing on the coast of Florida. 



In delineating the development of his hypothetical primitive 

 Mammal, the author makes a passing allusion to food : 



The animal, from grasping branches, may readily turn to grasping 

 leaves and fruit it may learn to grasp its food in its hand. As a sequel 

 it may learn to convey the food so grasped to its mouth with its hand 

 and so become a hand-feeder. It may take to grasping other objects which 

 come in its way. These objects may be useful for food or they may not ; 

 but the animal will learn to form an estimate of the object grasped. As 

 a sequel it may learn to feel, and to test novel objects with its hand. 

 Again, the mother may learn to grasp her off-spring in the precarious 

 circumstance of an arboreal infancy ; and she may adopt the habit of carry- 

 ing and nursing her baby. All these things are of vast importance. 



We have already seen that such and similar psychological 

 and sociological advantages as here alluded to, depend largely 

 upon the kind and quality of the food and upon the methods 

 of getting it. We have found that psychological and socio- 

 logical evolution require a perennial demand for restraint such 

 as is actually entailed in the symbiotic relation. Whether an animal 





