174 



SCIENCE. 



[N. S. Vol. VII. No. 162. 



SCIENTIFIC LITERATURE. 

 Traits de Zoologie Concrete. — La cellule et les 



protozoaires. Delage et Herouard, Paris. 



1896. 527 pages ; 870 illustrations. 



Tills volume, the first of a series to be pub- 

 lished by Delage and Herouard, inaugurates a 

 new departure in zoological text-books. The 

 authors point out that the usual text-books 

 (German and English) are not sufficiently de- 

 finite and that the student, especially a begin- 

 ner, has extreme difficulty in getting a mental 

 picture of the animals which comprise any 

 specific group. They maintain that the ordi- 

 nary text-book, in dealing with such a group, 

 introduces the subject by a few pages of com- 

 parative anatomy. The various organs and 

 systems of organs are described for the group 

 as a whole, but independently of any given 

 animal, while exceptions to the common type 

 are only casually mentioned. This introduc- 

 tory section is usually followed by an enumera- 

 tion of the sub-divisions of the group and each 

 subdivision is then treated in the same way as 

 the group, beginning with the comparative 

 anatomy, which is still vague and impersonal so 

 far as the specific forms are concerned, and 

 ending with a very short description of one or 

 two characteristic -genera. Nowhere in the 

 chapter is any one animal completely described, 

 and the student is confused by the variety of 

 forms casually mentioned and bewildered by 

 the numerous exceptions. Our authors regard 

 such a text-book as 'abstract,' dealing neither 

 with comparative anatomy nor systematic zo- 

 ology but falling weakly between the two. In 

 presenting their own ' concrete ' zoology their 

 aim is to avoid the evil above mentioned and to 

 leave in the mind of the reader a complete 

 mental picture of the structure of some type 

 specimen of each group. 



To take the place of the introductory sections 

 of the usual text-books, they give a complete 

 description of all the parts which make up a 

 type specimen of the class or order in question. 

 For this type specimen either some one form is 

 chosen which represents the average of the 

 group or an ideal form is created from the 

 imagination. Such a form, whether imaginary 

 or real, makes what the authors call the mor- 

 phological type (Type morphologique). The 



description of this type specimen xs very com- 

 plete, comprising morphology, physiology, re- 

 production, regeneration, etc., while copious 

 footnotes give further and more detailed infor- 

 mation concerning special parts or historic 

 connections. The description of the morpho- 

 logical type is followed by more condensed 

 descriptions of the common genera, while the 

 forms which are closely related are enumerated 

 in footnotes. By describing so many they 

 avoid exceptions to statements and so make 

 the way clear to the student for every form or 

 group of forms he reads about. Five hundred 

 and thirty genera are actually described in the 

 text, while half that number at least are men- 

 tioned in footnotes. Each genus is accompanied 

 by a figure, sometimes colored, in which all of 

 the parts are shown. 



Fifty- eight pages are devoted to a general 

 consideration of the cell and its functions. 

 Here the structure, chemical composition and 

 physiology of the cell, including nutrition, re- 

 production, fertilization, etc., are described in 

 a general way, while extended footnotes give 

 the main points on controverted questions in 

 cellular biology. In this portion Delage follows 

 pretty closely the lines of his own cytological 

 researches, and when he deviates from them he 

 is not always happy in his guide. For example, 

 in his extended review of Fol's principle of the 

 Quadrille of the Centers it is difficult to see 

 why he ignores Wilson's complete disproval, 

 and while cognizant of Boveri's and Mathew's 

 work on the subject comes to the conclusion 

 that Fol may still be right. 



By far the largest part of the volume is de- 

 voted to the Protozoa (470 pages), and here we 

 find their text-book plan completely worked 

 out, although the simplicity of structure of the 

 Protozoa gives little opportunity for testing the 

 value of their color scheme, according to which 

 the various organs are depicted in specific 

 colors. 



In the classification adopted the Protozoa are 

 divided into the usual four classes — Khizopoda, 

 Sporozoa, Flagellia and Infusoria. The further 

 subdivisions are only occasionally difTerent 

 from the usual classification. The authors fol- 

 low Lankester in giving to the Mycetozoa the 

 same taxonomio value as the Helioza and 



