470 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
stinging cells have a muscular investment, to which is attached a pretty 
long, thin, solid stalk which passes to the supporting lamella. 
Heliotropism in Hydroids.* — Dr. H. Driesch has observed helio- 
tropic phenomena in the growth of Sertularella polyzonias. The stolons 
produced in unfavourable conditions instead of persons, are at first 
positively, and after the production of daughter-stolons, negatively helio- 
tropic. They arise on the side of the mother-stolon turned towards the 
light. 
Porifera. 
Pseudogastrula Stage in Development of Calcareous Sponges.f — Mr. 
A. Dendy has had an opportunity of studying the development of Graniia 
labyrinthica ; while within the maternal tissues the embryo lies in a cavity ; 
as the embryo increases in size the capsule in which it lies becomes 
correspondingly enlarged ; the side of the capsule next to the adjoining 
layer of spicules becomes flattened, while the opposite side bulges out into 
the flagellated chamber and forms a kind of blister over which the delicate 
wall of the chamber becomes tightly stretched. The embryo obviously 
receives nutriment from the mother sponge, probably through the medium 
of the endothelial cells. The granular cells of the embryo absorb 
nutriment from the maternal tissues, increase in size, proliferate rapidly, 
become invaginated mechanically, and when they have done absorbing 
nutriment become arranged in a hemispherical mass of large ovoid cells, 
highly charged with food-granules and an investing epithelial layer. 
The embryo is now ready to lead an independent existence, and the 
internal mass of granular cells seems to be a supply of food which enables 
it to wander for a long distance before becoming fixed. By degrees this 
food is absorbed and used up, and then the invagination of the ciliated 
cells takes place and the embryo becomes attached. It is for this reason 
that in the gastrula stage the internal granular mass of cells is no longer 
visible. This mass does not seem to have anything to do with the 
formation of mesoderm. 
Anatomy of Hircinia, a new Genus of Sponges. :£ — M. H. Fol 
brings forward some evidence to show that those authors have been in 
error who have regarded the fibrils of Hircinia as the work of an un- 
known parasite ; these fibrils are, on the contrary, an integral part of 
the sponge. The family Filiferse ought, therefore, to be re-established, 
as it is the most certain and best characterized of all the proposed divisions 
of Horny Sponges. 
The name of Sarcomas Georgi is given to a large blackish sponge 
which is found in abundance near Nice, and is about the size of a man’s 
head. A short description is given of it from which it appears that it 
is intermediate between Spongelia and Aplysina, which it resembles by 
the characters of its skeleton, and Hircinia and Euspongia, which it 
approaches in the disposition of its canalicular system. 
Key to the Nomenclature of Sponge Spicules.§ — Dr. B. von Lenden- 
feld calls attention to a “ nomenclator spiculorum ” prepared by Prof. 
* Zool. Jahrb., v. (1890) pp. 147-56 (3 figs.). 
t Proc. Roy. Soc. Victoria, 1890, pp. 93-101 (1 pi.). 
X Comptes Rendus, cx. (1890) pp. 1209-11. 
§ Biol. Centralbl., x. (1890) pp. 131-5. 
