188 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
which one or more ecdyses are required after the maturation of the 
testes before copulation is possible ; here one ecdysis is all that is 
needed. Bathyporeia pelagica is the female, and the form described as 
B. Bobertsoni is the copulatory male of B. pilosa. It follows that the 
so called dimorphism of male Amphipoda is really a case of progenesis 
as in some other Crustaceans. 
Maturation of the Ova of Cyclops.* — Dr. Y. Haecker has studied 
the ova of various species of Cyclops , in order to determine the precise 
moment at which a reduction of chromatin elements takes place. Differ- 
ing from Boveri, who refers the reduction to a period in the history of 
the germinal vesicle antecedent to the expulsion of the polar bodies, 
Haecker finds by careful observation that the reduction takes place in 
the expulsion of the first. 
Movements in the Brain of Leptodora.f — Prof. B. Wiedersheim 
describes a remarkable region in the brain of Leptodora hyalina, in 
which granules and cells and vacuoles appear to be very mobile, chang- 
ing their form or position while examined. The mobile zone is that 
with which the main nerves are connected, and must therefore be of 
great morphological and physiological importance. Instead of being 
rigid the central nervous substance has the power of active movement, 
but what this precisely means has yet to be discovered. 
Hermaphroditism of Apodidae.i — The Eev. H. Bernard has investi- 
gated the structure of Apus cancriformis , the reproduction of which has 
been the cause of so much speculation. As is well known, this species 
is remarkable for the rarity of its males, and Mr. Bernard now shows 
that it is really hermaphrodite. The discovery commenced with a 
study of Lepidurus glacialis , which was found , to be hermaphrodite. 
A. cancriformis and L. product as were then investigated, and in both it 
was found that the sperm-forming centres are scattered here and there 
among the rich branchings of the segmental diverticula of the genital 
tube. They occur either at the tips of such branches, where the eggs 
ordinarily develope, or as slight lateral bulgings of the same. Further 
details and drawings are promised. 
The origin of this secondary hermaphroditism is to be found in the 
manner of life of these animals, which are always in danger of being 
cut off from their kind. The males of the Apodidae seem to be 
generally smaller than the hermaphrodites, aud this is the only point of 
sexual dimorphism which they exhibit ; on the other hand it will be 
remembered that in the Cirripedia this sexual dimorphism is much moie 
marked. 
Development of Ascidicolous Copepoda.§ — M. E. Canu remarks 
that circumstances have led to a remarkable condensation of the 
embryogeny of these Crustacea. In the Notodelphyidae the first Nauplius 
has, in addition to the three pail’s of characteristic appendages, the 
indications of two pairs of maxillae and two pairs of thoracic legs. The 
endoderm forms a compact cellular mass ; on its dorsal surface there are 
* Zool. Anzeig., xiii (1890) pp. 551-8 (1 fig.). 
t Anat. Anzeig , v. (1890) pp. 673-9 (5 figs.). 
X Nature, xliii. (1891) pp. 343-1. Jeuaische Zcitschr. f. Xaturwiss.. xxv. (1891) 
pp. 337-8. § Comptes Rendus, cxi. (1890) pp. 919-20. 
