No. i.J 



STUDIES UPON HYDROMEDUSAE. 



39 



delicate sheath of perisarc secreted over the ends was the first 

 indication of special activity and regeneration. This usually 

 occurred at any wounded point. It became specially marked 

 at the points of contact of the grafted specimens. The first 

 effect of the sectioning of the specimens preparatory to their 

 being placed in contact was a pronounced contraction of the 

 coenosarc within the tubular perisarc, and the closure of the 

 cut ends of the enteric cavity. This was usually, however, 

 soon followed by an outgrowth till the 

 coenosarc of the two specimens came 

 into contact, when the secretion of the 

 extra perisarc proceeded as a joint opera- 

 tion, though sometimes by a single one, 

 if its activity and response were the more 

 prompt. Cf. Figs. I and 2. 



Following this the contact of the two 

 became more intimate, the healed ends 

 united with each other, fusion being fol- 

 lowed by the absorption of the terminal 

 portions and the consequent confluence 

 of the enteric channels and their con- 

 tents. 



In the experiments no apparent dif- 

 ference was noticeable as to anything 

 like polarity, the parts uniting orally, abo- 

 rally, or otherwise, with equal freedom 

 and promptness. With species of Eu- 

 dendrium and Pennaria this was demon- 

 strated with absolute certainty, the directions of the branches 

 making any mistaking impossible. Cf. Figs. 2-4. 



In these species the sexes are distinct, and experiments in 

 grafting specimens of the opposite sexes were quite as prompt 

 and perfect as otherwise. There would seem, therefore, to be 

 not only no definite differences of polarity as seems to be the 

 case in Hydra, but no sexual difference in so far as regenera- 

 tive or coalescence capacity is concerned. It remains to note 

 results as to grafting different species. With none of these 

 are the distinctions sufficiently clear to warrant positive con- 



FIG. 4. 



