Vol. i.] Torrey—Mery. — Regeneration in Sagartia Davisi. 215 



a factor in the result. Davenport has reported thai "by feeding 

 to repletion, division already begun could be delayed, even 

 apparently prevented." in 8. luciae. Our own experiments 

 pointed in a similar direction, but were not conclusive. There 

 is no question that when food in the shape of a small amphipod 

 or morsel of flesh is seized by a dividing polyp, the process of 

 division ceases tor a time; the tension in the elongated foot 

 decreases, the centers of the mesenterial systems draw together 

 while remaining quite distinct, and do not move apart until the 

 food is digested and disposed of. But similar delaj may he 

 caused by strong mechanical stimulation at short intervals. And 

 it is questionable whether it is the mechanical or chemical stimu- 

 lation of the tissues of the body by the food, or their abundant 

 nourishment li\ absorption of the products of digestion, that is 

 at the root of the matter. The fact thai aquaria polyps which 

 show the effects of starvation for long periods by actually 

 decreasing in size, do not appear to divide, gives some coun- 

 tenance to the former view. 



(1>) The regenerative processes succeeding fission of this type 

 are not sufficiently distinct from those succeeding those of the 

 second type to warrant a separate description. For this reason 

 they will be described after fission of the second type has been 

 considered. 



2. The second method of non-sexual reproduction in 8. 

 davisi to be considered resembles the process described by Mrs. 

 Thymic. 



((/) Fission is not preceded by a rearrangement of mesenteries 

 about two centers, and is usually completed within twenty-four, 

 often within fifteen hours (i.e., over night). It may result in 

 the formation of two, three, four or five independent pieces 



which may 1 qua] in size but are usually unequal, especially 



when there are more than two. The tear begins on one side, 

 involving all tissues from column wall to oesophagus inclusive. 

 Meanwhile, the moieties separate as in fission of the first type, 

 and the tissues on the other side of the body between the two are 

 put upon the stretch. The prompt completion of the division 

 leads ordinarily to but two individuals, the tear proceeding in 

 general perpendicularly to the major mouth axis. It occasion- 



