200 [September 



SOME NEW BOOKS 



A French Treatise on Zoology 



Trait^ de Zoologie Concrete. Vol. I. La Cellule et les Protozoaires. By Yves 

 Delage and Edgard Herouard. Pp. xxx. 584, with 870 col. figs. Paris: Schleicher 

 Freres, 1896. Price 25 francs. 



This 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 



