336 A. J. GoUfarh 



tissues at which the tentacles of the new hydranth are clearly 

 discerned. Under normal conditions two days is required. Un- 

 der adverse conditions regeneration may not take place for 

 four, five, six or more days. Regeneration does not extend over 

 this entire period, at least in so far as visible changes are con- 

 cerned. There is a latent period, durmg which no visible changes 

 obtain and which normally covers but a few hours, butwhich under 

 unwholesome conditions may extend over several days. Once 

 regeneration begins development proceeds normally in about 12 

 hours. So that adverse conditions increase not the actual period 

 of regeneration but this latent period. 



In large stems the younger (distal) portions always regenerate 

 polyps at least one day before the older (basal) parts. When 

 stems were cut into three equal parts. Experiment 3, new polyps 

 appeared on the different pieces in the following order: 



TABLE 14 

 Polyps reg;"nerated on 2d day 3d day 4th day 



Distal thirds 8 polyps i additional polyp i additional polyp 



Middle thirds o 9 polyps i additional polyp 



Basal thirds o 6 polyps 4 additional polyps 



The distal thirds regenerated polyps earlier than the middle pieces 

 which in turn regenerated polyps before the basal thirds. 



To determine whether the two cut ends at any level of a stem 



regenerate at the same time, the above pieces of stems were used. 



A, B, C represents the distal, middle and basal pieces, re- 



j spectively. At the cut b c, b is the basal end of the distal 



1^ piece, and c the distal end of the basal piece. It was found 



^ that the b ends on A pieces regenerated on the average in 



B practically the same tune as the c ends on B pieces, and 



similarly for the b and c ends on the B and C pieces. It 



If was found that the b ends regenerate first, just as often 

 ^ '7 as the c ends and as often as the b and c ends regenerated 

 simultaneously. 



Although the distal region of a large stem regenerates polyps 

 within two days or at least one day before the basal region, vet 

 small pieces cut from the distal region (Experiment lo) never pro- 

 duce polyps before the third day and often not till the fourth day. 



