2/O 



C. M. CHILD. 



length of the tentacles occurred during the period of reduced 

 water-pressure. The failure of the tentacles to regain their 

 original length is probably due to the loss of vigor observable in 

 all specimens kept without food for a long period and the con- 

 sequent diminution in internal water-pressure and in the power 

 of growth. Regenerated tentacles never attain the length of the 

 original tentacles and similarly those tentacles elongating after 

 reduction never attain the original length. 



In this experiment the process of reduction did not pass beyond 

 the first stage. The tips of the tentacles did not shrivel, but re- 

 mained healthy and became distended again after closure occurred, 

 though the original length was never attained. It is possible 

 that the frequent partial distension of the tentacles during the 

 intervals between reopening of the aboral end was sufficient to 

 prevent the death of the tissues. As was noted in a previous 

 paper ('04$) the pieces must be reopened every few hours in 



order to prevent partial distension in the intervals, 

 \{/Y but this is impracticable for the long time necessary 



for perfect results. Consequently the method is by 



no means perfect. 



Series /(?. 



September /j, /poj.--In six large specimens 

 the aboral half of the body was split by a longitudi- 

 nal cut into two parts (Fig. 7). 



The object of this experiment was not tentacle 

 reduction but the duplication of the aboral end 

 and consequently the lengths of the tentacles were 

 not determined as frequently during the earlier 

 stages as in experiments on tentacle-reduction. 

 Later, however, when it was observed that these 

 specimens would afford interesting evidence upon 

 this point, measurements of the marginal tentacles were made 

 regularly. 



The split aboral portions of these specimens rolled in various 

 ways and closure was greatly delayed, the delay being further 

 increased by the frequent rupture of the delicate new tissue in 

 consequence of contraction during the necessary examinations. 



