^54 Mr. H. J. Carter on the Reproductive 



Dr. Grant's observations were made at Leitli, in the Firth 

 of Forth, during the months of October of one to that of March 

 of the following year {op. et loc. cit.), and I have found ovi- 

 gerous specimens of Isodictya simulans and Halichondria san~ 

 guinea here in the montli of January. So that it is impos- 

 sible to say in the present state of our knowledge wherher 

 the reproductive process in the marine sponges is confined to 

 any particular season or period, or is going on throughout the 

 year. 



Most of the sponges which were sent to me by Mr. Wilson 

 from " Port Phillip Heads," on the south coast of Australia, 

 were in an advanced ovigerous condition, in which the ger- 

 minal vesicle was, for the most part, still visible, and these 

 were dredged in the month of January, which corresponds to 

 our summer. 



Now, from the marked characters of the ovum, its large size, 

 and the long time it remains visible in the sponge before its 

 exit, it is much easier to be seen than the almost infinitely 

 smaller spermatozoon, which never grows beyond a certain 

 size and then quickly disappears. 



I have already stated that Lieberkuhn discovered the sper- 

 matozoa of the sponge in 1856, which was just thirty years 

 after Grant had discovered the ova in Halichondria panicea 

 &c., since which many have described and delineated them in 

 different sponges, to wit: — Hackel in Cahispongice^ml'&ll (1)*; 

 Einier in a species of Renieraj in 1872 (2) ; F. E. Schulzein 

 Halisarca lobidaris, in 1877 (3) ; MetschnikofF in HaUsarca 

 Dujardiniy in 1879 (4) ; Keller in his Chalinula fertilis^ also 

 in 1879 (5) ; and Polejaeff in Sycandra raphanus, in 1882 

 (6). "While Lieberkuhn, Schulze, MetschnikofF, and PoldjaefF 

 respectively have delineated the spermatozoa (in abundance) 

 within the " spermatoa " tj aiid separately out of them, so that 

 in these instances we have representations of them in both 

 conditions. 



But although both Schulze and Polejaeff have kindly 

 furnished me with admirable preparations of them while 



* (1) Jenaisclie Zeitschrift f. Med. &c., Bd. vi. p. 644. 



(2) Arcbiv f. mikroskop. Anat. Bd. viii. Heft 2, p. 28]. 



(3) Zeitschrift f. wiss. Zoologie, Bd. xxviii. p. 24, and Taf. iii. figs. 17 

 and 18. 



(4) lb. Bd. xxxii. p. 352, Taf. xx. figs. 2, a, b, c. 



(5) lb. Bd. xxxiii. p. 330, Taf. xviii. figs. 5 and 6. 



(6) Sitzungsb. d. k. Akad. d. Wiss., math.-naturw. Classe, Bd. Ixxxvi. 

 Abth. 1, 1882, p. 276 &c. Taf. i. & ii., Nov. Heft. 



t Spermatoa : " The nucleated cell in which the spermatozoa are 

 developed" {Owen). Ap. Pascoe, 'Zoological Classification,' p. 298, 

 Glossary, 2nd ed. 



