36 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
total ; the conical blastomeres surround an undivided core. After the 
preliminary cleavages, the blastoderm (blastolecithe) becomes distinct 
from the yolk (deutolecithe) ; a zone of small cells surrounds a non- 
nucleated internal vesicle. The blastoderm becomes immediately double, 
differentiating the two primary layers. This is comparable to the ex- 
tension of the “ cicatricula ” in Porcellio and its conversion into the blas- 
toderm. The vitelline membrane disappears quickly, and is replaced 
by a cuticular layer, perhaps corresponding to a cuticle of a nauplius 
moult. 
The body of the embryo diminishes in size as the yolk is absorbed ; 
and splits dorsally in a peculiar fashion, as if bent on itself. At the 
two ends of the cleft there develop two rigid annexes, transversely 
elongated. These dorsal organs are adaptations peculiar to the embryo 
and without significance for the adult. The dorsal cleft and the separa- 
tion of the two regions which result from it has its homologue in the 
development of the crayfish, though its precocious appearance there has 
led to its being misinterpreted as gastrular. 
It is evident, the author concludes, that an acquaintance with the 
development of Asellus is necessary to an understanding of the other 
forms ; and a full comparison is promised. 
Freshwater Copepoda and Cladocera of Portugal.* — MM. J. De 
Guerne and J. Richard give a first list of these Crustacea. They 
enumerate in all 25 species, all of which are known and most of which 
are common in Europe. This appears to be the first list which has 
been given of these Crustacea from the fresh waters of Portugal. 
Annulata. 
Epigamy and Schizogamy.f — M. A. Malaquin discusses these two 
phenomena in Annelids. In epigamy the whole sexual individual is 
affected, the eyes increase in size, the notopodia of the median and pos- 
terior regions change and acquire natatory setae. Such changes, first 
observed in Nereidae, are also known in Syllidae and Hesionidae. In 
schizogamy, only a part of the animal acquires the characters of sexuality, 
separating off and swimming freely. The part may acquire a differen- 
tiated head with appendages and large eyes, but it has no mouth, and is 
wholly reproductive. Various aspects of this schizogamy (which must 
be carefully distinguished from schizogenesis, are illustrated by Syllis 
(// aplosyllis) hamata Clp., Trypanosyllis , S. prolifer a Krohn, S. arnica 
Qtrfs., and S. ( Typosyllis ) hyalina. What the author particularly insists 
on is that in Autolytus longeferiens St. Joseph and Exogone gemmifera 
Pag. both epigamy and schizogamy are included in one life-cycle. 
Combined Nucleoli.f — M. A. Michel treats particularly of combined 
nucleoli, as observed in the eggs of the Annelids. These bodies have 
been found in the tissues of various animals, but the author has confined 
his researches to the eggs of Nephtliys and Spiophanes. The bodies in 
question contain one part which is solely granular, and stains with 
safranin more than the rest of the egg, and another clear refractive 
* Bull. Soc. Zool. France, xxi. (189G) pp. 157-9. 
t Zool. Anzeig., xix. (1896) pp. 420-3. 
X Coniptes Rendus, cxxiii. (1896) pp. 903-5. 
