286 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
intra vitam with neutral red, when removed to fresh- water, will lay red 
eggs from which stained young will hatch. Agar’s experiments are 
criticized. J. A. T. 
Early Development of Summer Egg of Simocephalus vetulus. — 
H. Graham Cannon {Quart. Journ Micr. Sci., 1921, 65, 627-42, 1 pi., 
1 fig.)* Each egg of this Cladoceran is laid in ayolky mass of foam, 
and subsequently forms a primary egg-membrane. Cleavage is com- 
pletely superficial and apparently indeterminate. The first differentia- 
tion of the blastoderm is the appearance of a group of vacuolated yolky 
cells on the ventral side of the embryo. This is called the “ ventral 
mass.” It subsequently differentiates into a few large cells with very 
large nuclei which form the genital primordium, surrounded laterally 
and posteriorly by ectomesodermal cells, and anteriorly to this a 
mesendodermal mass of cells from which arises the mesendoderm. The 
genital primordium, surrounded laterally and posteriorly by inwardly 
growing ectomesodermal cells, invaginates and becomes internal by the 
lips of the invagination growing together and fusing. The mesendoderm 
grows backwards as a solid mass of cells, which subsequently spreads 
out flat and becomes indistinguishable from the laterally-lying mesoderm, 
and from this layer the endoderm separates as a solid rod in the median 
plane. J. A. T. 
Arctic Copepoda in Passamaquoddy Bay. — A. Willey ( Proc . 
Amer. Acad. Arts and Sci, 1921, 56, 185-96). The plankton in this 
branch of the Bay of Fundy includes Galanus hyper boreus, Euchseta 
norvegica, and Metridia tonga , three Arctic species. It is especially 
remarkable that the rare males of the hyperborean Galanus were found 
in comparatively shallow water a little above the 45th parallel of 
latitude. J. A. T. 
Adaptations in Copepods. Lazar Car. — Glasnik {Rev. Soc. Nat. 
Croatica, 1921, 32, 175-84, 8 figs.). An interesting essay on the 
detailed adaptations of the appendages and other external features of 
Copepods, showing that the joints, the spines, the setm are mechanically 
effective. “ The smallest spine and the minutest seta has its signifi- 
cance,” and has been fashioned in relation to an end. The organism is 
purposive in relation to the differentiation of its organs, showing 
“ intelligence without consciousness.” _ J. A. T. 
Annulata. 
Affinities of Histriobdella homari. — F. Mesnil and M. Caullery 
( Comptes Rendus Acad. Sci., 1922, 174, 913-7, 5 figs.). The maxillary 
apparatus in this interesting type is identical in plan, structure and 
connexions with that of Euniceidse, and the resemblance points to 
genetic affinity. The cephalic appendages recall those of Ophryotrocha. 
The absence of a setigerous apparatus suggests simplification, but there 
is marked differentiation in the nervous and genital systems. It seems 
that the type should be regarded as a degraded Euniceid, and not as a 
primitive Archiannelid. J. A. T. 
