Mabch 10, 1899.] 



SCIENCE. 



369 



Oceania, and, incidentally, by Bunting, in 

 Hydradinia. The most nearly comparable 

 observations, so far as I have been able to 

 discover, are those recently reported by 

 Andrews in Hydra. 



This work was begun at the Marine Bio- 

 logical Laboratory in 1897, continued during 

 1898, and is still in progress. It is hoped 

 that a fuller account, with definite illus- 

 trations, may soon appear. 



Grafting Experiments upon Hydromedusce. 

 Chas. W. Hargitt. 



In course of previous work upon regen- 

 eration among the Hydromedusse, the prob- 

 lem of grafting was forcibly impressed upon 

 me, and during the summer of 1898, at the 

 Marine Biological Laboratory, was under- 

 taken and followed up during nearly two 

 months, and with results as briefly outlined 

 below. 



It was undertaken to show the practi- 

 cability of uniting sections of different in- 

 dividuals, different species and even genei-a. 

 The first work undertaken was upon 

 Hydroids, chiefly Tubularians, e. g., species 

 •of Eudendrium, Pennaria, Parypha, Clava, 

 ■with only one series of experiments upon a 

 ■Campanularian. The latter was for some 

 reason almost wholly negative in results. 

 In all the former the results were unusually 

 successful, no less than 10% responding 

 within the limits indicated. To merely 

 summarize : 



1. No difficulty was found in securing 

 perfect union between segments of the same 

 species in from twelve to twenty-four hours. 

 A delicate sheath of perisarc overlapping 

 the proximal ends was first secreted, and 

 this was followed by organic union of the 

 cosnosarc of the hydroid . The grafting was 

 equally successful whether made by oral, 

 aboral or alternating contact of the seg- 

 ments. Abundant heteromorphism was se- 

 cured along with the other results. 2. 

 It was equally easy to secure union of 



male and female specimens of the same 

 species. 3. If the distinctness of Agassiz's 

 species of Eudendrium dispar and ramosum 

 is to be maintained — a fact which has seemed 

 to me doubtful — then there was secured a 

 ready grafting of different species. 4. In 

 no case was I able to secure successful graft- 

 ing between diffei'ent genera. This was 

 tried repeatedly with several, but in each 

 case with negative results. 



The second problem undei-taken was upon 

 the medusiB. The most accessible form was 

 Oonionemus vertens, and the results ob- 

 tained were on this form alone. Grafting 

 was made possible only by the expedient of 

 paralyzing the specimens by emargination 

 of the entire bell, thus removing the coordi- 

 nating centers. This done, there was no 

 more difficulty in securing perfect union of 

 different portions of the body than with the 

 hydroid forms. It mattered little from what 

 portion of the body taken, or in what rela- 

 tion placed, perfect union was usually se- 

 cured in from 24 to 48 hours. Two medusje 

 grafted orally recovered nervous activity, 

 and even exhibited a definite coordination, 

 the double medusa acting as one. 



The Life-History of Dicyema. William 



Morton Wheeler. 



A STUDY of the Dicyemidffi (Dicyema colu- 

 ber, n. sp.; Dicyemennea Whitmanii, n. sp., and 

 Dicyemodeea sceptrum, n. gen. et n. sp.), par- 

 asitic in the kidneys of the West Coast 

 Octopus (0. punctatus'),wa.s undertaken with 

 a view to answering the following questions 

 concerning the life-history of these animals : 

 1. What are the relations of the nema- 

 togenic and rhombogenic individuals to each 

 other? 2. What is the meaning of the 

 so-called infusoriform embryo ? 3. What is 

 the meaning of the infusorigen ? An ex- 

 amination of the parasites of one hundred 

 Octopus of different ages led to the conclu- 

 sion that the Dicyemidse first reproduce as 

 nematogens for several generations, but that 



