1893.] NATURAL SCIENCES OF PHILADELPHIA. 79 



Now as to how the Orientals accomplished the production of 

 double-tailed forms of fishes. I believe they did this by taking the 

 eggs of the normal species of gold-fishes and shaking them, or dis- 

 turbing them in some way, as did Professor Weber with the eggs of 

 the pike. They would thus get some complete double monsters, some 

 with two heads and a single tail, and some with double tails. Mani- 

 festly the complete double monsters would be unlikely to survive. 

 Those most likely to survive would be those with only a duplication 

 of the tail. These being selected and bred would in all probability 

 hand onward the tendency to reproduce the double tail, a tendency 

 which could become very fixed and characteristic if judicious 

 selection were maintained by interested fanciers and breeders, such 

 as are said to exist in Japan, where these fishes of the finest double- 

 tailed races command high prices amongst the wealthy and culti- 

 vated classes. 



If the remarkable peculiarities of the Japanese Gold-fishes were 

 produced as suggested above, and there seems to be no more likely 

 method of their origination, the whole question of the inheritance 

 of mutilations is reopened from a totally new point of view, and one 

 that cannot be assailed by Weismann and his following with much 

 show of success from their present attitude toward these questions. 

 It is clear, however, that we have here a most promising field for 

 experimental inquiry and one that should be at once cultivated in a 

 practical way. 



That the direction of the regeneration of lost parts may be affected 

 by the plane of mutilation is sufficiently well attested by the exper- 

 iments of Barfurth on the tails of tad-poles, some of which I have 

 successfully repeated. If the tip of the tail were snipped off" exactly 

 at right angles to the axis of the body, the tail was regenerated of 

 the normal form and straight backward. If at an acute angle, 

 regeneration took place so that the new tip was directed either 

 upward or downward, according as the inclined, regenerating cut 

 surface looked upward or downward. Such facts cannot be dis- 

 missed as useless in connection with the problem of inheritance in 

 general, if they have any bearing upon the questions raised in con- 

 nection with the inheritance of mutilations as viewed in the preced- 

 ing discussion. It is not unlikely that Barfurth's results do have 

 some bearing upon these questions as here viewed. If the plaue of 

 mutilation or line of removal of digits affects their direction of 

 growth, as seems likely from Barfurth's and my own experiments, 



