84 PROCEEDINGS OF THE ACADEMY OF [1893. 



tions and forces, and that even these leave a reminiscence of their 

 effects upon the germs, the development of which they thus indi- 

 rectly affect. What again shall be said in such cases of the effect 

 of such external or physical agencies or conditions in modifying the 

 development of future generations, as seems to be proved by the 

 history of the domesticated races of Japanese Gold-fishes? Weis- 

 mann must now own, if the preceding views can be sustained, 

 that he is beaten upon his own ground, and also admit that he has 

 been in error from the beginning as to the non-transmission to the 

 germs of characters that have been acquired by the body of the 

 parent. 



The domesticated races of Japanese Gold-fishes outstrip every 

 known form of domesticated animal in the extent to which they 

 have been modified, and it is therefore strange that Mr. Darwin 

 should have devoted so little consideration to them in his works, 

 In one of his botanical works Mr. Darwin makes the suggestion 

 that the bilateral halves of the Bilateralia may have arisen by 

 longitudinal concrescence of two similar individuals of opposite sex. 

 This suggestion of his, as to the origin of the bilaterally sym- 

 metrical condition, may be dismissed as exceedingly improbable and 

 unfortunate, and as in direct conflict, moreover, with the known 

 mode of the development of monsters with double axes. Such mon- 

 strous races, as is proved by the morphology of the adult Japanese 

 Gold-fishes, their known analogies to the development of double 

 vertebrate monsters, have been produced almost beyond a shadow of 

 doubt by mutilational interference with the early processes of nor- 

 mal development, and this monstrous mode of development has 

 become hereditary. 



The procedure by means of which the Orientals originated their 

 peculiar races of Gold-fishes I believe was more exactly as 

 follows : After the blastoderm had spread over about one-third or 

 more of the surface of the yolk, the eggs were shaken or violently 

 disturbed. This proceeding would cause the production of one or 

 more new embryonic axes at the rim of the blastoderm near the 

 original axis, but the new axes would not develop a head, but 

 would, as a result of the operation of the principle of concrescence, 

 soon fuse with the caudal end of the original or first-formed embry- 

 onic axis. This would cause a doubling, more or less complete, of 

 the caudal end or urosome of the embryo. In this way it may be 

 supposed that the partially double urosome of these singular fishes 



