68g 
[November, 
Analyses of Books . 
it is consumed, and that to an unpleasant extent. It is also un- 
fortunate that, in spite of this addition, the mixed spirit cannot 
be bought without a further addition of shellac, unless the con- 
sumer can comply with certain onerous conditions. It need 
scarcely be said that, save for the varnish-maker, shellac is one 
of the most unfortunate “ denaturising ” additions that could 
have been selected. 
Judging from the present part, we should expecft that two more 
volumes will be required to complete the work on its present 
scale. 
A Treatise on Comparative Embryology. By Francis M. Bal- 
four, LL.D., F.R.S. In Two Volumes. Vol. II. London: 
Macmillan and Co. 
We have here the second and concluding part of Dr. Balfour’s 
great work, and can now form some adequate idea of the labour 
and research which have been required in its compilation. In 
the first ten chapters of the volume the author expounds the 
developmental history of the Chordata from the Cephalocorda up 
to the Mammalia. In the eleventh chapter we find a short com- 
parative review of the formation of the germinal layers and of 
the early stages in the development of the Vertebrata, the author 
treating successively of the formation of the gastrula and the 
behaviour of the blastopore, with the origin of the hypoblast ; 
the mesoblast and notochord ; and lastly, the epiblast. From 
the last-mentioned are formed the central nervous system, and 
the epidermis, which also takes a main share in the formation of 
the organs of special sensation. 
From the hypoblast are formed the epithelium of the digestive 
canal, of the trachea, bronchial tubes, and air-cells, the cylin- 
drical epithelium of the ducffs of the liver, pancreas, &c., and the 
spheroidal secreting cells of the pancreas and other glands. 
From the monoblast are formed the true skin, the muscles, the 
skeleton, the vessels, generative and urinary organs. It is par- 
ticularly noted that the epithelium of the urinary glands, though 
resembling the hypoblastic epithelium of the alimentary canal, is 
nevertheless mesoblastic. 
The interesting question of the growth of the vertebrate em- 
bryo is next discussed. On this subjedl two views prevail. The 
author, in common with the generality of embryologists, holds 
that, e.g., the Elasmobranch embryo arises from a differentiation 
of the edge of the blastoderm, extending for some little distance 
inward from the edge. This differentiation is considered to 
comprehend the rudiments of the entire embryo, except the yolk- 
