Factors m Regeneration 333 



the stem; in pieces i V inch long the trip from one to the opposite 

 end takes from \\ to 3 minutes. As the granules accumulate at 

 this end the stream moves more and more slowly until it finally 

 ceases. There may be a respite of a few minutes and then the 

 stream courses in the opposite direction at first slowly then faster 

 and faster, and finally slowly again as the granules pile up at the other 

 end. The performance is repeated over and over again; the time 

 for each trip may vary considerably. Now and then groups of 

 granules are violently whisked about or "tremble," the result of 

 ciliary movement of the endoderm. Granules were never seen to 

 pass out of the prostomium of the living polyp. After disintegra- 

 tion of the polyps dark red masses^' were frequently observed 

 marking the spot where the polyps had been. 



The current in a lateral branch may be continuous with that in 

 the main stem, moving at the same rate and in the same direc- 

 tion, or it may be independent, and even contrary to the stream 

 in the stem. The central stream may be continuous or divided 

 into two or more independent streams. Though the coenosarc 

 in branches and stem is continuous, the streams within the 

 coenosarc of these parts may behave independently. The contin- 

 uity of the coenosarc may be permanently broken by pressing a 

 stem firmly with the side of a needle. The coenosarc is cut into 

 two parts which separate more and more from each other. If 

 gently pressed, a dent is temporarily produced in the coenosarc 

 which slowly recovers its normal shape. 



The number of hydranths that arise from the basal cut end 

 of pieces is closely associated with the amount of coenosarc near 

 such ends. Other conditions being equal the more coenosarc at 

 or near a cut end the more hydranths produced. Several condi- 

 tions must, however, be taken into account. A large stem does 

 not necessarily contain more coenosarc per unit of length than 

 another one-half as long. Much depends on the more or less con- 

 tracted condition of the coenosarc. If it be attenuated, as in 

 rapidly growing branches, it will have per unit of length less regen- 

 erative potency than the more concentrated coenosarc usually 



"These dark red bodies are probably analogous with the red bodies resulting from the metabolic 

 changes in Tubularia, studied by Bickford '94; Stevens '01 and '02, and Loeb '91, and Morgan loc. cit. 



