450 T. H. MORGAN. 



individuals regenerated only one segment each. In one case 

 one segment must have been cut oflF and one regenerated. 



The results of these tables have a direct bearing on the con- 

 ditions found in adult worms, and recorded in a previous 

 section. Those worms in which both openings of the vasa 

 deferentia were found on a segment anterior to the fifteenth 

 may have been, in most cases, the result of the loss of ante- 

 rior segments, and a subsequent incomplete regeneration. We 

 cannot affirm that all cases were the result of the process, 

 because, in the light of other facts, it is not improbable that 

 such variations may have come from the embryo. 



These records also show us that regeneration of the anterior 

 end will not account for any of those cases where the vasa 

 deferentia open on a metamere posterior to the fifteenth, for 

 in no cases were more segments generated than amputated. 



What the result would have been in the cases recorded below 

 where a worm regenerated many segments, after amputation far 

 posterior to the fifteenth segment, I cannot tell. The worms 

 were not kept for a long enough time to determine whether 

 or not reproductive organs would ever have appeared. 



In the preceding and following tables it will be noticed that 

 in many cases the position of the openings of the vasa deferentia 

 is recorded, and when these were not found the segments con- 

 taining the seminal receptacles (9 — 10 — 11 normally) are re- 

 corded. These landmarks were located after regeneration had 

 taken place. This served as a check for those cases where the 

 number of segments amputated had been previously recorded, 

 and in the other cases gave fairly accurate evidence as to the 

 number of segments that had been cut oflf. 



In the next two tables, — the results of the first series of ex- 

 periments, — a large number of recorded segments were cut off 

 to find the limit of the power to regenerate anterior segments. 



