6 Giel. 
C(ELENTBRATA, 
lying outside the continuous endodermal wall has led observers to sup- 
pose that the testis was ectodermic in origin. 
47. [Varenne, a. de.] De I’origine de I’oeuf chez les Hydraires. L. c. 
pp. 345-347; Ann. N. H. (6) viii. pp. 321-323. 
In the types examined Carnpanularia fiexuosa, Plumularia echinata, 
Sertularia pumila, Gonothyrcea loveni, Podocoryne carnea, and Ohelia 
geniculata. Whatever may be the later history of the gonophore, the 
ova do not originate within it, but can be distinctly traced as develop- 
ments of ordinary ectodermal cells. 
48. Weismann, a. Beobachtungen an Hydroid-Polypen. Zool. Anz. 
iv. pp. 61-G4. 
I. Pulsiren des Korperschlauchs. 
II. Selbstandige Bowegungen des Ectoderms. 
From observations first made on Coryne pusilla^ it appears that distinct 
rhythmical waves of contraction pass down the body-walls, which would 
assist the action of the cilia of the endoderm in causing a movement in the 
contained fluid. The ectoderm appears moreover to be capable of pseudo- 
podial movement altering the relation of the body-wall to its tube. 
49. . Beobachtungen an Hydroid-Polypen. iii. Die Entstehung 
der Eizellen in dar Gattung Eudendrium. L. c. pp. 111-114. 
60. . Observations sur les cellules sexuelles des Hydroides. Biblio- 
th^que de l’(5cole des Hautes Etudes, Section des Sciences Naturelles, 
xxiv.. No. 3, 4 pis. Ann. Sci. Nat. (6) ii. 
The question as to the place of origin of the sexual products of 
Hydroids is one upon which very various opinions have of late years 
been adduced. The ectoderm and endoderm have, in turn, been put for- 
ward as giving rise to both eggs and spermatozoa. Kleinenberg, in 
speaking of Hydra, and F. E. SchuUze of Cordylophora, state that both 
products are derived from the ectoderm, a result which the author con- 
firms. Grobben has observed the same origin in Podocoryne carnea, 
and F. E. Schultze in Sarsia tuhulosa. The Hertwigs have shown 
the same ectodermal origin of both elements in numerous Medusce ; 
and lastly, Ciamician has shown the same origin in Tubularians, the 
author having arrived at the same conclusions even before Ciamician’s 
publication. On the other hand, the author has clearly demonstrated both 
products to have an endodermic origin in Plumularia, Serttdarella, and 
Eudendrium, The spermatozoa may be derived from the ectoderm, and 
the ova from the endoderm. E. van Beneden has shown this to be the 
case in Hy dr actinia, Fraipont in Carnpanularia, and the author in Gono- 
thyroea. These various methods of origin may exist in the same family. 
The author shows that there are a large number of species, of genera, and 
even of entire families, in which the sexual elements do not originate in 
the reproductive individuals, but in the parenchyma of the colony, the 
ccenenchyme of Milne- Edwards and Haime, the ccenosarc of Allman. 
Such an origin the author terms cosnosarcal, in contradistinction to a 
hlastoidal origin ; and he would recognize two types of Hydroids — coeno- 
genous (coenosarcogenous), and blastogenous. To the latter group, belong 
