QUARTERLY CHRONICLE OF MICROSCOPICAL SCIENCE. 83 
lot’s memoir shows throughout a due recognition of the 
labours of earlier observers, such as Grenacher, Meissner, 
Siebold, and others. 
Arthropoda.—In the second part of Koll. und Sieb. Zeit- 
schrift, 1874, Bobretzky has a paper on the embryology of 
Oniscus murarius, which is important from the apparent suc- 
cess which the author has obtained in cutting sections of such 
small and friable eggs as those of this Isopod. An earlier 
paper by the same author, in the Russian language, is referred 
to, in which a similar treatment of the eggs of Astacus fluvia- 
tilis and Palemon serratus had led to similar results. We 
venture once for all to appeal to Russian embryologists, who 
are at present so greatly distinguishing themselves in this 
line of research, to abstain from publishing the accounts of 
important new observations in a language which is inacces- 
sible to western Europeans. We submit that, on account of 
the literary importance of those languages in other directions, 
it is desirable, for scientific purposes, to employ either 
English, F Pele or German as the language of science ; and 
simply on account of the number of cultivated persons 
throughout the civilised world who are familiar with one or 
other of these three languages, we should advocate the adop- 
tion of English or French in preference to German, by scien- 
tific writers whose native tongue is not included under the 
three languages specified. 
Bobretzky finds in Oniscus the representatives of the three 
chief embryonic cell-layers present in the Vertebrata. The 
so-called food-yelk becomes organized, or, to a large extent, 
converted into cellular elements, and is regarded by him as 
hypoblast. Previously to this, by segregation of a patch of 
plastic yelk and its cleavage, an epiblast has been formed 
which covers, by gradual extension, the entire surface of the 
egg. Mesoblastic cell elements take their rise between this 
and the large mass of granular yelk. It is not clear from 
Bobretzky’s observations whether the hypoblast-cells which 
appear throughout the granular yelk-mass arise there by a 
deep segregation, or whether they penetrate to that position 
by extension from the “ germinal heap” which forms below 
the epiblast at one pole of the egg. The subsequent dif- 
ferentiation of these cells is in accordance with the most 
usual (but, as we believe, not invariable) disposition of such 
elements. The epidermis and great nerve-ganglia are formed 
from the epiblast cells, as also the fore part and hind part of the 
alimentary canal. The hypoblastic cells arrange themselves 
so as to form a straight fore and aft middle intestine, joining 
the fore and hind in-pushings of the epiblast, to wit, pharynx 
