398 
SC M MARY OF CURRENT RESEARCHES RELATING TO 
which three are recognised, it is noted that specific differences cannot 
be recognised in this genus with any accuracy, except in living speci- 
mens, and that coloration is so variable that it is almost useless as 
a standard in classification. The tendency to violet colour among 
Bermuda echinoderms is alluded to. 
Ccelentera. 
Cnidosacs of Siphonophora.* — Dr. K. C. Schneider has investigated 
these structures in both the Physophora and the Calycophora. The 
latter have always an elongated form and are called Cnidosacci atorti 
in opposition to the coiled Cnidosacci contorti of the Physophora. In 
the former there is a central core of endoderm without cell limits, but 
with nuclei. Close to it there lies the tongue-shaped band which is de- 
rived from the endoderm. On the upper surface the cnidoblasts are 
arranged in a straight band consisting of seven rows of cells each con T 
taining a nematocyst. The cnidoblasts are supported by an elaborate 
framework of elastic fibres connected to the distal end of the tongue- 
shaped band. The band of cnidoblasts is covered by a thin layer of 
glandular cells, and at either side of it lies a band of large glandular 
cells. 
In the Physophora the cnidosacs are spirally coiled, and the band of 
•cnidoblasts contains more cells than in the Calycophora. In the fully 
developed cnidosacs there is a mere trace of an endodermic core, the 
endoderm being almost used up in the formation of the four tongue- 
shaped bands. There are also other noticeable differences from the 
cnidosacci of the Calycophora. The paper includes an account of the 
development of both types, and a summary of the observations of others. 
As to the discharge of the nematocysts, observation showed that this 
occurred only on direct contact between the cnidosacs and the prey. 
Contact with the terminal thread of the cnidosac, or even traction on 
this, did not produce discharge. Th discharge is not produced by 
the tongue-shaped band, is apparently not due to muscular action, 
and is perhaps the result of a chemical process induced by an external 
stimulus. 
Pigment of Blue Coral.f — Prof. A. Liversidge states the results of 
some preliminary experiments on the blue pigment present in the blue 
•coral ( Heliopora ccerulea). He describes the separation of the pigment 
and the action of various reagents. The known blue pigments from 
other animals are briefly considered, and it is pointed out that the 
pigment from the coral differs more or less from all the rest. 
Branchiocerianthus urceolus Mark.J — Dr. Oskar Carlgren has a 
short note on this form which was described by Prof. E. L. Mark § as a 
■“ new type of Actinian.” Carlgren believes that it does not belong to 
the Actinozoa at all, but is a Hydrozoan, at least closely allied to the 
genus GorymorpJia , and that the so-called “ gills ” are in reality sexual 
buds. The note is based merely on Mark’s “ preliminary report.” 
* Arbeit. Zool. Inst. Univ. Wien, xi. (1899) pp. 65-116 (4 pis.). 
t Journ. and Proc. Koy. Soc. N.S. Wales, xxxii. (1898) pp. 256-68. 
% Zool. Anzeig., xxii. (1899) pp. 102-3. 
§ Hull. Mus. Comp. Zool. Harvard, xxxii. (1898) pp. 145-54. Cf. this Journal, 
1 898, p. 633. 
