ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 399 
Edible Medusae.* * * § — K. Kishinouye describes two rhizostomatous 
medusae, Bhopilema esculenta Kishinouye and Bh. verrucosa sp. n., 
which occur in Japanese waters and are used for food, and also as bait 
for file-fish (Monacanthus) and sea-breams ( Pagrus ). The latter are said 
to accompany the shoals of the medusae. 
Porifera. 
Histology of Hexactinellidae.f — Herr F.E. Schulze obtained, through 
the North German Polar Expedition of 1898, some new Hexactinellid 
sponges so well preserved as to make it possible to describe the choano- 
cytes, which have not hitherto been seen in these sponges. They con- 
sist of a broad basal plate, a narrowed hourglass-shaped stalk, and a 
slightly conical collar from the centre of which springs the flagellum. 
The basal plates are fused to one another to form a continuous membrane 
only occasionally perforated by the pores of the chambers. The nucleus 
is basal, and projects only slightly above the level of the basal plate. 
The distal ends of the cells immediately below the collar region are 
united together on all sides with only occasional openings correspond- 
ing to the chamber pores. The choanocytes thus differ markedly from 
those described for other sponges. It is to be especially noticed 
that the collars of the adjacent cells show no trace of fusion, that is, 
there is no trace of “ Sollas’ membrane.” 
Name of Tetranthella fruticosa (0. Schm.).+ — Dr. Joh. Thiele has a 
short note on the correct name and the systematic position of this much- 
named sponge. Oscar Schmidt originally described it under the two 
names of Suberites crambe and S fruticosa ; but it is not a Suberites. 
The two fragments described by Schmidt belong to the same species, 
and according to Thiele the correct name is Crambe crambe (O. Schm.) 
and von Lendenfeld’s name of Tetranthella fruticosa must be dropped. 
Further, Thiele has found that the sponge contains a few isocheles, 
which he believes proves that it belongs to the Desmacidonidse. The 
skeleton of the sponge is described in detail. 
Protozoa. 
Behaviour of the Nucleus in Conjugating Infusoria.§ — Herr H. 
Hoyer has made a detailed study of the phenomena of conjugation in 
Colpidium colpoda St. The material was fixed in a mixture of corrosive 
sublimate and potassium bichromate, and, after the usual treatment, 
was imbedded in paraffin and cut into sections. The individuals 
when about to conjugate attach themselves together in pairs by union of 
the anterior ends. Shortly afterwards the micronucleus of each enlarges, 
and, by a process of modified karyokinesis, divides into two. The two 
nuclei so formed again divide without the intervention of a resting 
stage. Each individual now contains four micronuclei. Of those three 
in each disappear, and the single remaining nucleus in each approaches 
the septum dividing the individuals, increases in size, and divides by a 
* Znol. Jahrb. Abth. Syst., xii. (1899) pp. 205-10 (1 pi. and lfig.). 
t SB. Akad. Wiss. Berlin, 1899, pp. 198-209 (3 figs.). 
X Arch. Naturgeschirhte, Ixvi. (1899) pp. 87-94 (1 pi.). 
§ Arch. f. Mikr. Anat., liv. (1899) pp. 95-134 (1 pi. and 2 figs.). 
