No. 494] NOTES AND LITERATURE 



141 



lengthened the interval before the next moult by eighteen per- 

 cent. The longer the time intervening between a moult and 

 the removal of appendages the longer the following moult was 

 postponed through the influence of the resulting regeneration, 

 although the less likely was regeneration to ensue. 



Emmel's experiments also seem to show that the retarding 

 influence is due to the regeneration phenomenon and not to 

 the injury sustained, since in all of his experiments those ani- 

 mals that failed to regenerate new limbs did not have the 

 moult following the operation postponed. 



In the young lobsters the regeneration process retarded their 

 growth at times more than twenty-four per cent. 



Dr. Zuelzer, having the contradictory results of Zeleny and 

 Emmel in mind, has undertaken a similar study on the little 

 crustacean Asellus. Agreeing with Zeleny, she finds that in the 

 majority of cases moulting occurs at shorter intervals if re- 

 generation is taking place. The rapidity of moulting depends 

 upon the time elapsing between the last moult and the time of 

 operation, an important factor, as shown also by Emmel. 



If the animal is operated upon during the moulting stage 

 or shortly after, the following moult is usually hastened by the 

 regeneration phenomenon. When more time intervenes between 

 the moult and the amputation of the limbs the tendency is to 

 delav the first moult following the operation, but to hasten the 

 second and third moults. Should the amputation of append- 

 ages immediately precede a moult the moult occurs normally, 

 but no regeneration is shown, the next moult r — • 



regeneration 



the third moult is aecelen 



regenerating limbs increased in size. Occasionally 

 operation preceded the moult by a considerable 

 regeneration occurred, although the moult may 

 hastened. 



When the two antennae are cut at different leve 

 leave stumps of unequal lengths, the longer one leg 

 a slower rate than the shorter, so that the m-i-mal 

 length is again established. Zuelzer considers tins 

 "compensatory regulation." that is. the short -nnn| 

 the longer one to regenerate slower than it \\..u . <»t i 

 done in order to reestablish their equality m ""-j^ 

 ference in growth rates may be equalh wel exp ai 

 to the levels at which the cuts were made on the t* 

 for the fish's appendage that 



