COSMIC PHILOSOPHY 



the line of least resistance becomes to a certain 

 extent a line of traction. A good illustration is 

 afforded by the gradual evolution of the circu- 

 latory system as we ascend in the animal scale. 

 In the lowest animals which possess any nutri- 

 tive fluid perceptibly distinct from the proto- 

 plasmic jelly of which their bodies are com- 

 posed, this fluid percolates here and there at 

 seeming random, its course being determined 

 by local pressures, just as in the case of rain 

 water trickling through the ground. Now as 

 we ascend to higher animals, we find that the 

 nutritive fluid has wrought for itself certain 

 channels, to which it confines itself, and which 

 gradually become more and more definite in 

 direction, and more and more clearly demar- 

 cated from the adjacent portions of tissue. Un- 

 til, when we reach animals of a high type of 

 structure, we find the blood coursing through 

 permanent channels, the walls of which contract 

 and expand in such a way as to assist the blood 

 in its progress. A similar explanation is to be 

 given of the genesis of the contractile fibres of 

 muscle, as due to the continuance of molecular 

 undulations along certain lines. 



When we come to the nervous system, we 

 find most completely realized all the conditions 

 requisite for the rapid establishment of perma- 

 nent transit lines. The clusters of molecules of 

 which nerve tissue is composed are more heter- 



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