ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
131 
thuriidse, form a group for which the old name of Aspidochirotae will be 
appropriate. 
Ccelentera. 
Stinging-Cells.* — Dr. N. Iwanzoff has investigated the stinging- 
cells of a large number of Coelentera. All are modified epithelial cells 
(cnidoblasts), and each encloses a single nematocyst. The nematocyst, 
or capsule, may be round, oval, or cylindrical in form ; the thread is a 
tubular invagination of the capsule-wall. Only in Anthozoa are there 
threads which are ruptured out instead of being evaginated. There are 
always two kinds of stinging-cells in an animal, and in most Siphono- 
phora there are four or five kinds. 
The capsule-wall has two layers — the inner thicker, the outer con- 
tinuous with the lasso. At the opening of the capsule there is usually a 
plasmic lid. Within the capsule there is a gelatinous, not fluid sub- 
stance, which stains with anilin dyes, swells up in water, and has 
corrosive, acrid qualities. It is the swelling which expels the lasso. 
Water enters when the lid is thrown off, or when the beginning of the 
lasso is protruded in consequence of external pressure. 
The proximal part of the thread is often stronger, and may then be 
called the axis body ; it lies straight in the capsule, while the rest 
of the thread is coiled. Both axis-body and thread may be smooth, 
or beset with roughnesses, bristles, or spines arranged in three spirals. 
The smooth thread is doubtless the more primitive. 
The nematocysts have both a mechanical and a chemical effect. The 
spines of the axis-body may fix firmly in the victim, and the poisonous 
gelatinous material may enter the wound. 
Herr Iwanzoff describes the structure of the cnidoblast in detail — 
the peripheral layer, the distal fringe of bristles or the single cnidocil, 
the supporting (non -muscular) processes at the proximal end, and so on. 
The development is also described. 
No nematocysts were found in sponges, though Eimer has described 
their occurrence. Those in Turbellaria are noticed, and those in 
iEolididae. 
Coral Reef at Funafuti.! — Such borings as Prof. W. J. Sollas was 
able to make on this reef lead him to think that its structure is that of 
a coarse “ sponge ” of coral with wide interstices, which may be either 
empty or filled with sand. The chief constituents of this sand appear 
to be large Foraminifera, of the genera Orbitolites and Tinoporus. 
Though the boring proved a failure, a thorough investigation of the 
fauna and flora was successfully made, while important soundings were 
taken by Captain Field, K.N. ; these appear to Prof. Sollas to support 
Darwin’s theory of the coral atolls, but the bathymetrical limit of coral 
life is a subject which stands in need of renewed investigation ; our 
accepted conclusions rest on too frail a basis. 
Ccelentera of the ‘ Caudan ’ Expedition 4 — The report on the Coelen- 
terates collected by Prof. Koehler in the Bay of Biscay has been drawn 
* Ex Bull. Moscow, 1896, 99 pp. and 3 pis. 
t Proc. Boy. Soc. Lond., lx. (1897) pp. 502-12. Nature, lv. (1897) pp. 373-7 
(5 figs.). 
x Kesultats Scient. de la Campagne du { Caudan,’ fasc. ii. (1896) pp. 299-323. 
