200 [September 
SOME NEW BOOKS 
A FRENCH TREATISE ON ZOOLOGY 
TRAITE DE ZooLocie Concrire. Vol. I. La Cellule et les Protozoaires, By Yves 
Delage and Edgard Hérouard. Pp. xxx. 584, with 870 col. figs. Paris: Schleicher 
Fréres, 1896. Price 25 francs, 
TuIs is the first instalment of a work which, if it finishes as it has 
begun, will be of the greatest value, since it combines completeness 
and erudition with a method of treatment at once highly original and 
well adapted to the end in view. 
The primary object of the authors is to smooth the path of the 
student and to help him in his difficulties, and in their preface they 
are at pains to explain how it is intended to bring about this result. 
Every one knows how difficult it is, when commencing the study of a 
group of animals with the help only of an ordinary text-book of com- 
parative anatomy, to apply the more or less vague generalities of 
which such works are composed to the case of a particular form. 
The usual method of describing a group of animals in the text-books 
or treatises on zoology is to commence with a chapter or chapters in 
which the comparative anatomy of the group is described organ by 
organ in a purely abstract manner—that is to say, without reference 
to the remaining organs of the body. This is followed by a systematic 
portion in which the families or genera are catalogued and distin- 
guished by means of their external characters. The great defect of 
this mode of treatment is the want of any proper link between the 
abstract and the concrete, between the general and the par- 
ticular. The beginner who is as yet unfamiliar with the group in 
question finds an extreme difficulty in forming a clear idea of how a 
particular form is organised in its entirety, since he has to combine 
in his mind a brief summary of its external characters with the rather 
vague mental image of its anatomy which he constructs by wading 
through the comparative chapters and picking out such portions as 
may apply to the form under consideration. Hence text-books of 
this class, though extremely valuable to the advanced student or 
teacher as works of reference, are confusing to the learner, who 
requires above all things something real and concrete, upon which to 
found his general notions. 
It is not every student who has the time or opportunity to obtain 
the empirical basis so necessary for a clear grasp of the main prin- 
ciples, by consulting the special memoirs or monographs dealing with 
the forms he is studying, and in order to help him out of the diffi- 
culty a large class of practical text-books of zoology has sprung up 
in recent years, in which particular forms are chosen as typical 
examples of the larger systematic groups and described in great 
detail. In this way a division of labour has come about whereby the 
treatise of comparative anatomy is supplemented and elucidated by 
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