564 



THE AMERICAN NATURALIST 



[Vol. LI 



That the oral and ch)acal terminations just described 

 do in reality ro])i-o-ent r(\u-eneration, has been verilied by 

 observation of the conr-e of regeneration in the labora- 

 tory after ex |)(M-i mentally cutting the holothurians lin 

 various ways (cf. Crozier, 19156). Certain specimens 

 also hnve 1)('(mi tabulated as '^regenerating" when their 

 apiu'ni'.'uicc ( I'^iii". -2. r), backed up by dissection, suggested 

 that tlu'\ had jii-t completed division and had not yet 

 begun to r<'gciu'rate. These specimens lacked either a 

 cloaca, or tlie stone ring and buccal structures, depending, 

 obviously, on their former relation to the complete indi- 

 vidual from which they were derived. 



The evidence that the regeneration found occurring 

 under natural conditions results fronkthe self-division of 

 adult holothurians, involves two considerations. The 

 first concerns (a) the relative size of the regenerating 

 animals, and (b) the relative frequency of anterior and 

 posterior ends noted as regenerating. The second has to 

 do with direct observations of self-division. 



