QUARTERLY CHRONICLE OF MICROSCOPICAL SCIENCE. 89 
aid, and the usual appliances of a laboratory, master for him- 
self the whole question, as it at present stands, in a practical 
way—the only way in which he should ever be called upon to 
master it. The directions at the end of the book for the 
treatment of the incubated and unincubated egg—as to open- 
ing, hardening, staining, cutting, and mounting—are simple, 
clear, and to be relied upon absolutely. 
The ‘Lehrbuch der Vergleichenden Embryologie der Wir- 
belthiere,’ by Professor Schenk, published recently (1874) at 
Vienna, is a book of a very different kind. It contains a 
large amount of information, and very beautiful woodcuts— 
chiefly (though not exclusively) derived from original memoirs 
on the development of Batrachia, Osseous Fishes,and the Chick, 
by Stricker, Klein, Oellacher, Gotte, and others. A certain 
number are original, and illustrate original observations, of the 
author. It does not in any way justify its title as a text- 
book of comparative embryology ; it rather furnishes some of 
the materials for such a treatise, which has yet to be written, 
and, indeed, cannot be written until more is known of the 
development of Amphioxus, the Cyclostomata, the Elasmo- 
branchs, and even of the Mammalia. Professor Schenk’s 
volume, with its numerous illustrations, will be found valu- 
able as a compilation from some of the most recent German 
writers on the embryology of the higher Vertebrata ; as such 
we recommend it to the advanced student of embryology ; 
but it must be understood that the material is not digested, 
nor of such a nature as to be useful to the commencing 
student. In this respect it contrasts strongly with the Eng- 
lish text-book above noticed. 
Schenk, on the Egg of Raja quadrimaculata, Bonap., whilst 
within, the Oviduct.—(‘ Wiener Acad. Sitzungsber.,’ Lxviii, 
1 abth., 1873, with one plate). 
A. Rauber, on the Embryonal Area of the Chick, in 
‘Centralblatt’? (Oct. 24). The author remarks that the em- 
bryonal area of the Bird is in comparison with that of the 
Osseous Fish only equivalent to the foremost portion of the 
latter. In this relationship, however, the conditions are 
given for the setting free, in the case of the Bird, of large 
portions of the germ in the formation of an amnion. 
The Formation of the Layers of the Blastoderm and of the 
Blood in the Hen’s Egg, by Alexander Gétte, is published in 
‘Max Schultze’s Archiv,’ vol. x, part 2. The deep cleav- 
age of the yelk discovered by Gétte, and announced in this 
paper, has been confirmed by Mr. Balfour, and a similar con- 
dition observed by him in the Dog-fish (see this Journal, 
October, 1874). 
