liKPORT OF nOMMlSSIOXERS OF INLAKD FISHERIES. 27 



This done, the remnants were cast overboard and considered done 

 for. But this was entirely a mistake, as was presentlj^ found out. 

 Five or six of these fragments not only retained life but renewed 

 the lost parts and became active again. Thus, instead of dimin- 

 ishing the pest these men were directly increasing it, since they 

 were making two or three star-fishes out of each captive. It was 

 a case of multiplication by division, which may be an invariable 

 paradox in mathematics but is by no means one in zoology." 



I have made some exi3eriments in order to find out what the ac- 

 tual powers of regeneration are. If the arm of a star be mangled 

 it will generallj^ drop off, or can easily be pulled off, always severing 

 its conne(;tion with the central disc at a certain fixed line. If 

 these stars be kept in a suitable car they will renew the lost arms. 

 If an arm be cut off at some distance from the disc it will regener- 

 ate a new tip. Double or rather forked arms were produced by 

 cutting off the tip of an arm and splitting the stump. Each half 

 stump, so to sj^eak, regenerated a complete tip. Such freaks are 

 sometimes found among the stars which come up in the dredge or 

 mop. 



Four of the five arms were taken off at the same time, and all 

 four regenerated. The arms which were removed, however, never 

 showed the slightest sign of regenerating the rest of the star-fish. 

 Another ex]3eriment, I cut the star-fishes into two parts, one having 

 three arms and the greater ]3art of the central disc, the other having 

 two arms and the smaller part of the disc. The smaller part in each 

 case died, while the larger lived. All but one of these specimens 

 were afterwards destroyed by other star-fishes in the aquarium. 

 One still survives and has lived for months in the same aquarium 

 with the stars which have, meantime, regenerated their lost arms. 

 This one, howev^er, has not showed the slightest sign of regenerat- 

 ing its lost parts, nor had the others before the}' were killed. 



More experiments must, of course, be made before a definite 

 conclusion can be reached, but I believe that the popular opinion 

 that two star-fish maj' be gotten from one, by cutting it up and 

 allowing the fragments to regenerate, is erroneous ; that only one 



