626 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Regeneration in Lower Crustacea.* — Herr Hs. Przibram points out 
that regeneration in Crustaceans is known only in Decapods and in the 
Isopod Ligea. He was thus led to try Asellus aquaticus, Cyclops , and 
three Daphnids. With Cyclops he got only negative results ; in Asellus 
he observed the regeneration of antennae and other appendages, just as 
Herrick states for Ligea ; in Daphnia the regeneration took a quite novel 
form. Removal of the eyes yielded no results. 
Annulata. 
Centrosome and Sphere in Nerve-Cells of an Invertebrate.f — Miss 
M. Lewis, while studying the finer anatomy of the nervous system of a 
worm belong to the family Maldaniae, found that it exhibited a very 
primitive condition, for it lies in the hypodermis, and in each segment 
gives off on either side of the body a large number of nerves, 35 or 
more. In these there are, among others, some giant-cells which are 
arranged without any discoverable regularity along the cord. They are 
usually elongated in one axis and have large and distinct nuclei. On 
the side of the nucleus which tends to be flattened or concave there are 
found the structures which may be called centrosome and sphere. We 
do not seem yet to have sufficient evidence with regard to the function 
of this central corpuscle and sphere of nerve-cells, but several facts 
plainly indicate that the body has a mechanical influence upon the 
protoplasm of the cell : 
(1) The concentric arrangement of the protoplasm around the central 
corpuscle. 
(2) The radiations which extend from this corpuscle. 
(3) The excentric position of the nucleus. 
(4) The flattening of the nuclear membrane on the side toward the 
sphere. 
(5) The outer band of protoplasm near the periphery. 
These facts all tend to prove that the central corpuscle is a 
mechanical centre, and therefore an active element in the cell. We can 
only determine whether it is truly homologous with the centrosome of 
actively dividing cells by tracing its previous history. If it can be 
shown that it has remained over from the last cell-division, then the 
presence of such a body as a true centrosome in a cell so conservative 
as a nerve-cell would be a matter of great theoretical interest, and 
Miss Lewis thinks that a strenuous effort should be made to solve the 
problem. 
Arenicola.f — Mr. H. M. Kyle has made a study of the renal and re- 
productive organs and post-larval stages of this worm. Arenicola is 
found on the sands of St. Andrews Bay in great abundance, and in all 
stages, from the young forms (three to four inches in length) to the 
older and larger (fourteen inches or more). The larger forms seem to 
vary in external appearance, according to the conditions in which they 
live. From clean dry sand a form is got of a fine golden colour, with 
a smooth and glossy exterior ; from the muddy clay flats a form is pro- 
* Zool. Anzeig., xix. (1896) pp. 424-5 (2 figs.). 
t Anat. Anzeig., xii. (1896) pp. 291-9 (11 figs.). 
X Ann. Mag. Nat. Hist., xviii. (1896) pp. 295-301 (3 pis.). 
