634 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
It rapidly increases during tlie pause, and reaches a maximum when in 
the form of chromosomes. The central mass of the sperm-aster derived 
from the middle-piece forms the centrosome in the sense of Boveri, and 
at first contains no distinguishable centriole. The centrioles first appear 
in the daughter-asters derived by the fission of the sperm-aster, and are 
probably formed by endogenous differentiation. The centrioles repre- 
sent the first stage in the form of a large reticulated erythrophilous 
centrosphere. It is not certain whether this body represents the entire 
substance of the original central mass, or only a part of it. 
Autotomy in Cucumaria planci.* — Dr. F. S. Monticelli describes 
remarkable processes of complete autotomy seen in that variety of 
Cucumaria planci Br. which occurs at Naples on a sandy bottom mixed 
with mud. The more typical form of the species is not known to show 
these. Three modes are described : — (a) by stricture, the least frequent 
case ; ( b ) by torsion, the most frequent case ; and (c) by stretching, as 
the result of which three individuals may arise from one. A period 
of preparation and initiation may be distinguished from the shorter 
period of division. The process is more leisurely than that in Synapta , 
and it also differs in giving rise to equivalent parts, each of which forms 
a new individual. Moreover, it is a defensive adaptation in Synapta, a 
reproductive process in Cucumaria. Monticelli has also made experi- 
ments in which, by cutting, ligaturing, and stretching, he artificially 
induced “ mecotomy,” and demonstrated the great power of regeneration 
exhibited by these Holothurians. 
Viviparous" Synapta ofithe West Indies.| — Mr. H. L. Clarke has 
recently had the opportunity of studying the anatomy and development 
of a Synapta found in Kingston Harbour, Jamaica, which is very pro- 
bably the species which Oersted described, in 1850, under the name of 
Synaptula vivipara. Of this species practically nothing is known, and 
the author gives, what will be useful, an account of its external cha- 
racters and internal anatomy. The eggs, which are unusually large, are 
set free in the body-cavity of the adult, but the author was unable to 
determine whether self-fertilisation takes place or not. The gastrula, 
which is formed by invagination, is well covered with cilia. It soon 
escapes from the membrane, is very active, and swims about freely in 
the body-cavity of the mother. Development takes place directly without 
any metamorphosis. The young remain in the body-cavity of the adult 
for an indefinite period. These animals live more or less in clusters of 
seaweed, on the roots of mangroves. They are very delicate, sensitive 
to changing conditions, and do not thrive in aquaria. Although differing 
in its manner of life from other members of the genus, this species, 
Mr. Clarke thinks, is a true Synapta. Probably the species described 
by Theel from Bermuda as S. picta is identical with it. 
Ccelentera. 
Nervous System of Ccelentera.f — Prof. S. J. Hickson gives an 
aocount of recent work on this subject. He tells us that the facts of the 
* Zool. Anzeig., xix. (1896) pp. 398-400. 
t Rend. Accad. Lincei Roma, v. (1896) pp. 231-9 (3 figs.). 
X Science Progress, i. (1896) pp. 101-7. 
