6 Goel. 
CCEL ENTE RATA . 
33. Merescu kowsky, C. D&veloppement des Spermatozoides dans la 
M^duse. ( Cassiopea borbonica). L. c. pp. 577-582. 
34. Mobius, IC. Wassergehalt der Medusen. Zool. Anz. v. pp. 586 & 587. 
35. PiLLsnuiiY, J. II. Development of the Planula of Clava leptostyla, 
Ag. Am. Micr. J. iii. pp. 181 & 182. 
36. Tullberg, S. A. On the. Graptolites described by Basinger and the 
older Swedish authors. Stockholm : 1882, 8vo, 22 pp. 
37. Varenne, A. de. Developpement de l’oeuf de la Podocoryne carnex. 
C. R. xciv. pp. 892-894. 
38. . On the Origin of the Spermatozoids in the Hydroids. Ann. 
N. H. (5) ix. pp. 133-135. 
39. . Recherches sur la reproduction des Polypes hydraires. Arch. 
Z. exper. x. pp. 611-710. 
40. . Recherches sur les Polypes hydraires (Reproduction et D<5- 
veloppement). Paris : 1882, 8vo, 104 pp., 10 pis. 
The question as to the place of origin of the sexual products in 
Hydroids still continues to call forth conflicting opinions, but we now 
appear to be coming nearer to the truth. It has been shown by Weis- 
mann [ rf Zool. Rec. xviii. Cod. p. 6] that, putting aside for the moment 
the question as to ectodermal or endodermal origin, the generative pro- 
ducts in either need not originate in special reproductive individuals 
(gonophores), but that they may originate in the parenchyme of the 
colony — the coenosarc ; and he proposed to distinguish a coenosarcal 
from a blastoidal origin, asserting that all Hydroids producing free- 
swimming Medusae , and probably numerous forms with fixed Medusa 
belong to the blastogonous group. The author of the present memoir 
had come to somewhat similar conclusions [cf. Zool. Rec. xviii. 
Ccel. pp. 5 & 6], but now he goes further, and shows that in the 
forms which he has studied — Campanularia Jlexuosa , Plumularia echi- 
nulata , Sertularia pumila, Gonothyrcea loveni , Podocoryne carnia , and 
Obelia geniculata — the ova or spermatozoa alike develope, whether ma- 
tured in fixed sporosacs, in Medusoids which remain fixed ( Gonothyrcea 
loveni ), or in Medusoids which have a free existence, in the coenosarc of 
the polyp, and, moreover, originate from endodermal cells. The author 
believes that previous observers who have put forward the ectoderm as 
the place of origin of the sexual products of either sex, have boon misled 
by the fact that, in many cases, although actually originating as stated 
above, such cells migrate even after they have reached the reproductive 
bud ; the endoderm reforms itself beneath the eggs or spermatozoa, and 
a new homogeneous membrane (stiitzlamella) is secreted by the newly- 
formed endodermal cells, which might easily be mistaken for the original 
structureless lamella — the latter, as well as the ectodermal layer, having 
become reduced, on account of the pressure exercised by the developing 
eggs or spermatozoa to an extremely thin layer, which, however, passes 
outside the sexual products. It has been usual to consider the gono- 
phores, whether these remain fixed (sporosacs) or become free-swimming 
