42 PROGRESS OF MICROSCOPICAL SCIENCE. 
as it occurs among sea-urchins, and he states that “ centres of attrac- 
tion appear, before each division, at two opposite poles of the yet 
absolutely intact nucleus, and seem to consist in a local fusion of the 
substance of the nucleus with the vitelline protoplasm, or perhaps an 
irruption of the protoplasm in the more fluid interior of the nucleus. 
At these two little masses of sarcode soon appear rays of sarcode, 
some of which extend into the interior of the nucleus from one centre 
of attraction to the other, while others diverge in the vitellus.” The 
author then remarks on certain points on which he differs from 
M. Biitschli, and states that the medium best adapted to bring out 
the true aspect is picric acid followed by glycerine. Osmic acid, he 
says, usually causes the disappearance of the extra-nuclear filaments. 
Researches on the Echini.—‘ Etudes sur les Hchinoidées, par 
S. Loven, from Kongl. Svenska, Vetenskaps-Akad. Handligar. Vol. ii. 
No. 7. 4to, with 53 plates. 1875.—The writer of the short notices 
in ‘ Silliman’s Journal’ states that this very important work, although 
published some time ago, has only just reached him. It is mainly 
devoted to a very thorough and complete study of the skeleton and 
external organs of the entire group of Echini. A few new forms are 
also described and figured. 
Structure and Movements of Dionea muscipula—An important 
paper was published on this subject in the beginning of the year by 
M. C. De Candolle, of Geneva; and in the September number of 
‘Silliman’s Journal’ Dr. A. Gray, who may be considered one of the 
first authorities on the subject, makes the following remarks :—‘ One 
noteworthy suggestion—which has already been made here—is 
that the sudden change of electrical current at the closing of the 
trap, ascertained by Burdon Sanderson (and much insisted on, on 
account of its accordance with what takes place in muscular motion), 
may have had its importance much overrated. The electro-capillary 
currents, which Becquerel long ago demonstrated in vegetable 
tissues generally, would almost necessarily be influenced in some 
such way by the displacements of liquid which would accompany 
any such abrupt change in the turgescence of the parenchyma. 
In some experiments made three years ago by Professor Trowbridge, 
of Harvard University (which, unfortunately, were not followed up), 
it was found that the strong bending of an internode of stem, with- 
out lesion, produced a similar electrical effect. M. Casimir De Can- 
dolle fairly deduces from his experiments the conclusion that animal 
matter is not necessary to the development and vigour of Dionea. 
He goes on to the conclusion that the animal matter of the insects 
caught is not directly utilized by the leaves. This does not follow. 
Very much evidence would be required to rebut the presumption that 
the organic matters absorbed are somehow (and even directly) 
utilized by the plant. The independent movement of the border of 
the trap with its fringe of bristles is explained by the anatomical 
structure, which is, as it were, distinct from that of the main body. 
The glands are stated to belong to the epidermis only; but the 
excitable bristles are connected by the cellular bulb with the suh- 
