REPORT OF C0MMISSI0NJ:RS OF INLAND FISHERIES. 85 



been made cm regeneration among crustaceans. A few words may 

 be added to indicate some of the theories which have been proposed 

 to explain the phenomenon of regeneration. 



THEORIES OF REGENERATION. 



Reamur was among the first to suggest a philosophical explanation 

 of regeneration. In the following words he expresses his belief that 

 each limb must contain an infinite number of eggs or egg-germs: 

 " We may suppose that these little limbs which seem to grow out were 

 inclosed in a little egg and that when a limb was broken off the same 

 juices which nourished this part were used to develop and bring to 

 birth the little germs of a limb inclosed in this egg.* 



Goodsir assumed the existence of glandular-like bodies at the base 

 of the limbs, which supply the germ of the new limbs; but the exist- 

 ence of such glandular bodies is not supported by the results of other 

 observers. 



Pfluger (1883) assumed that food material is taken up at the 

 wounded surface and organized into the substance of the new limb. 



Herbert Spencer elaborated a comparison of regeneration with the 

 process of restoring a broken crystal. He suggests that "analogous 

 forces" are at work both in the renewal of a part of a crystal and in 

 the regeneration of a limb. 



Two opposing views exist at the present time as to the origin of 

 the power of regeneration, of which Weismann is a representative of 

 one and Morgan of the other. Weismann concluded that the re- 

 generation power is a characteristic which has been acquired by nat- 

 ural selection. He found an important reason for this conclusion 

 in a supposed causal relation between the power of regeneration and 

 the liability to injury. Morgan, on the other hand, denies the exist- 

 ence of any such causal relations and concludes that the power of re- 

 generation is not the result of any selective agency of the environ- 

 ment, but that "regeneration is a fundamental attribute of living 

 beings "t 



*Herrick. U. S Fish Commission Report 1895. p. 106 

 tMorgan. Regeneration, p. 282. 



