350 SUMMARY OF CURRENT RESEARCHES RELATING TO 



them the young spicule. The doctrine, then, of Kowalevsky, that the 

 spicules arise from cellular elements, may probably be extended to 

 all the Alcyonarians. And the same would seem to hold for the 

 horny sheaths. These cells found in the mesoderm would seem to 

 have been derived from the ectoderm, whence cells have been observed 

 to wander into the middle layer ; as this has never been noted with 

 regard to the endodermal cells, we may conclude that the hard skeletal 

 parts of the Alcyonaria, whether spicula or horny sheaths, are 

 derived from the ectoderm. 



Porifera. 



Sponges of the Gulf of Triest.*— In his second paper on the 

 marine fauna of the Gulf of Triest, Dr. E. Graeffe deals with 

 the Spongiarife ; with which 0. Schmidt has already dealt. It 

 is pointed out that sponges have but few enemies ; some of the 

 species of Doris, Doriopsis, and Fissurella attack their outer layers ; 

 on the other hand, they have a number of parasites, AlgaB and 

 Chsetopod Annelids being the most conspicuous. Gammarida are 

 also not unfrequently found. Some silicious sponges have their 

 outer surface affected by small Aphroditeidas and by Hydroid 

 Polyps. 



In the list given by the author especial attention is directed to 

 the places in which they are found, and their time of reproduction, 

 with some notes on the localities of the ova and larvae. 



Spongiophaga in Fresh-water Sponges.t — Mr. E. Potts insists 

 that Mr. Carter is mistaken in considering that the slender curling or 

 twisted tendrils :j: of the statosphere of fresh-water sponges of the 

 genus Carterel'a § are parasites, as described by him under the name 

 of S]}ongiophaga Pottsi.\\ Prof. Leidy, by whom they were examined, 

 says that " there can be no question as to the tendrils being part of 

 the structure of the statoblast — homogeneous extensions of its inner 

 capsule." 



The function of the tendrils is apparently to meet the emergency 

 occasioned by the looseness of the skeleton structure, from which 

 the sarcode-flesh dying early washes away, most of the spicules soon 

 following in the winter floods. The eggs are thus left to the pro- 

 tection of the tendrils, which lap them together, bind them to the 

 remaining spicules or the roots of water-weeds or shore plants, or 

 assuming the role of the hair which the plasterer uses, bind the 

 deposited silt about them, and both to' the stones, where they await the 

 appointed time for a new growth. The resemblance in material 

 structure of these tendrils to that of the specialized hooks of some of 

 the Polyzoa is very striking. 



Mr. Carter, as the result of subsequent examinations,^ agrees with 

 Mr. Potts' view as to the filaments being in reality cirrous appendages 

 on the statoblasts and not Spongiophaga. 



* Claus' Arbeit., iv. (1882) pp. 313-21. 



t Proc. Acad. Nat. Sci. Philad., 1881, pp. 460-3. 



i See this Journal, i. (1881) p. 613. 



§ Ibid., p. 901. II Ibid., p. 901. 



«i[ Ann. and Mag. Nat. Hist, ix. (1882) pp. 390-6. 



