254 SUMMARY OF CURRENT RESEARCHES RELATING TO 



here and tbero in groups over tlic general ectodermal surface : no 

 gangliun-cells like those of Sycones were discovered. In the Ascones 

 (Homocoela) the ordinary ectodermic cells appear to perform also the 

 nervous functions. These results clearly show that the calcareous 

 sponges at least can no longer be considered as Protozoa. 



Our readers will remember that Prof. C. Stewart exhibited speci- 

 mens of Grantia comprcssa showing " palpocils " in 1880.* 



Occurrence of Flesh-spicules in Sponges.! — P. v. licndcnfeld 

 points out that flcsb-spiculcs are rare in other sponges than such as 

 possess a fibrous reticulate skeleton composed of closely packed 

 siliceous spicules. In confirmation of bis hypothesis expressed in a 

 previous paper,;]: that flcsb-spicules are of no great systematic value 

 and may occur in any family of sponges, be cites the discovery of a 

 species of the Aplysillidae with numerous anchors in the ground-sub- 

 stance, and a representative of the Spongida?, a sponge which would 

 otherwise bo undoubtedly referred to Cacosjiongia, containing 

 numerous truncate spicules in the ground-substance. 



Fibres of certain Australian Hircinidae.S— P. v. Lcndenfeld finds 

 amongst sponges of the Australian shores a series of forms possessing 

 the filaments characterizing the Hircinidfe of the same shape as those 

 of Hircina, but which do not appear so smooth. Under a 1/12 in. it 

 is possible to detect minute 6j)ots on their surface and on the fibres 

 of the horny skeletons. Those on the latter he considers to bo the 

 expression of the spongoblasts, which may not impossibly also form 

 the filaments and cause their spotted appearance. Filaments have 

 been observed growing out from ordinary fibres with which they may 

 have come in contact and been fixed there by succeeding layers of 

 spougiolin. Or they may be Oscillarians that have become covered 

 with a thin layer of horny substance, and subsequently absorbed by 

 the sponge and the vacant space filled Avith born-substance. A great 

 number of the Hirciuidaj possess a horn-fibre skeleton differing not 

 only from that of known Hircinida^, but from any known form of 

 horny fibre. Numerous minute horny fibres running in various 

 directions and anastomosing form a column of reticulate horny- 

 substance which corresponds to an ordinary main fibre. 



The pigmented cells in some horn sponges which possess filaments 

 may possibly tui-n out to be small algae living symbiotically with the 

 sponge. 



Development of Spongilla.|| — A. Goette has investigated the 

 developmental history of SponcjUla, with the result that he has 

 established its fundamental identity with that of sponges in general, 

 as previously described by him. The ectoderm of the larva atrophies 

 gradually, commencing at the border of the ectodermal orifice. 



The pseudogastrula of Sijcandra, Lencandra, &c., is really a pheno- 

 menon of ectodermal atrophy, and points to a primitive gastrula as in 



* See this Jownial, iii. (1S80) p. 560. 



t Proc. Linn. Soc. N. S. AVales, ix. (1884) pp. 493-4. 



X See this Journal, iv. (1884) p. 394." 



§ Proc. Linn. Soc. N. S. Wales, ix. (1884) pp. 641-2. 



II Zool. Anzeig., vii. (1884) pp. G7G-9 and 703-5. 



