LIFE AND THE COSMOS 291 



by natural selection. 1 Thus Du Bois-Rey- 

 mond: "One of the greatest difficulties pre- 

 sents itself in physiology in the so-called re- 

 generative power, and — what is allied to it 

 — the natural power of healing ; this may now 

 be seen in the healing of wounds, in the delim- 

 itation and compensation of morbid processes, 

 or, at the farthest end of the series, in the 

 re-formation of an entire fresh-water polyp 

 out of one of the two halves into which it had 

 been divided. This artifice could surely not 

 have been learned by natural selection, and 

 here it appears impossible to avoid the assump- 



1 "Still less explicable in anyway thus far proposed are 

 certain remedial actions seen in animals. An example of 

 them was furnished in § 67, where 'false joints' were de- 

 scribed — joints formed at places where the ends of a broken 

 bone, failing to unite, remain movable one upon the other. 

 According to the character of the habitual motions there re- 

 sults a rudely formed hinge-joint or a ball-and-socket joint, 

 either having the various constituent parts — periosteum, 

 fibrous tissue, capsule, ligaments. Now Darwin's hypothesis, 

 contemplating only normal structures, fails to account for 

 this formation of an abnormal structure. Neither can we 

 ascribe this local development to determinants : there were 

 no appropriate ones in the germ-plasm, since no such struc- 

 ture was provided for. Nor does the hypothesis of physi- 

 ological units, as presented in preceding chapters, yield an 

 interpretation. These could have no other tendency than to 

 restore the normal form of the limb, and might be expected 

 to oppose the genesis of these new parts." — Herbert 

 Spencer, "The Principles of Biology," Vol. I. New York 

 and London, 1909, revised and enlarged edition, p. 362. 



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