738 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
by superficial cleavage, and there has been a reduction in the amount of 
yolk. A close comparison is instituted between the mode of formation 
of the germinal layers in Brancliipus and the Cladocera, and, again, 
between Moina on the one hand, and Baplmia and Daphnella on the 
other. The process of yolk-absorption is next considered, and the author 
expresses his opinion that the yolk-cells are to be considered part of 
the mesoderm ; it is of importance to note that the yolk-cells become 
fat-body-cells in the developed organism. 
Dr. Samassa thinks that instead of proposing uncertain hypotheses 
on the origin of the germinal layers, it is more important to determine, 
in every separate case, by reference to the most nearly allied holoblastic 
forms, what have been the cenogenetic changes which have caused the 
yolk ; if this is done it is much easier to make out the palingenetic 
processes. 
The Cladocera show us that the resorption of yolk may be due to 
the mesoderm ; and as this is so we have no right, when the yolk-cells 
exhibit no relation to the enteron, to ascribe them to the endoderm. 
Copepoda of Liverpool Bay. * — Though three reports on the 
Copepoda. of the Liverpool district have been published in recent years, 
Mr. I. C. Thompson has become acquainted with so many fresh forms 
in the last four years, that it has been thought advisable to draw up a 
complete report of all the species recorded from the district. Before 
1885 only six species had been noted, the present report deals with 136, 
eighteen of which are new to British seas, and eleven of them are new to 
science. Among the latter is a representative of a new genus of the 
Misophriidse, which the author calls Herdmania ( H . stylifera sp. n.) ; 
though minute, being only 0*6 mm. long, it is said to be remarkably 
elegant ; it was taken at 39 fathoms, about twelve miles from Port Erin. 
New Choniostomatidse.f — MM. A. Giard and J. Bonnier describe 
under the names of Spheronella microcephala and Salenskia tuberosa two 
new parasitic Crustacea from the French coast. This is the first time 
that a member of the Choniostomatidae has been met with on the coasts 
of France. Both the new species were found in the incubatory cavity 
of specimens of Ampelisca which had been made sterile by parasitic 
castration. 
Reproductive Elements of Apus and Branchipus.f — Mr. J. E. S. 
Moore thinks that the development of the chromosomes in the sperma- 
tozoa of BrancMpus is partly dependent on a fusion of the globules, 
which gives rise to the reticulate appearance. Progress of such a fusion 
would produce the one-sided figure described by Hermann in the sperma- 
tocytes of the Salamander, and lead to the formation of a limited number 
of chromosomes, all on the nuclear periphery. The author shows that 
during the changes that occur there are in the resting spermatocytes 
three dark points (pseudosomes) whose appearance corresponds in every- 
thing but number with the centrosomes of previous authors. The fusion 
spreads beyond the nucleus, and the chromosomes are suspended to the 
pseudosomes ; these last retreat towards the periphery, and in connection 
with this motion an axis tends to set up, round which the spindle-figure 
* Trans. Liverpool Biol. Soc., vii. (1893) 56 pp. (21 pis.). 
t Comptes Rendus, cxvii. (1893) pp. 446-9. 
X Quart. Jouru. Micr. Sci , xxxv. (1893) pp. 259-83 (2 pis.). 
