November 13, 1896.] 



SCIENCE. 



729 



accorded and made use of by me for the bene- 

 fit of the object in view. 



E. V. d'Invilliers, 

 Philadelphia, Pa. 



SCIENTIFIC LITERATURE. 

 General Principles of Zoology. By Richard 



Hertwig. Translated by George W. Field. 



Henry Holt & Company, New York. 1896. 



The most pressing need for teaching elemen- 

 tary zoology in American schools is a suitable 

 text-book ; one that treats the general principles 

 in a way that clothes with flesh the skeleton 

 of systematic zoology ; one written with 

 genius that holds the attention and inspires. 

 It must be clear and compact. Prof. Hertwig' s 

 ' Lehrbuch der Zoologie ' is such a book, and an 

 English edition will doubtless give an impulse 

 towards better teaching and better discipline in 

 acquiring the foundations of animal biology. 

 The separation of the ' General Principles ' from 

 the ' Systematic Part ' as an independent vol- 

 ume may be regarded as an advantage, since its 

 clear, comprehensive, though brief, generaliza- 

 tions and discussions make it a useful hand- 

 book for teachers, students and general readers 

 who want to find and understand the latest 

 position of the science. 



In the introduction the author defines the 

 purpose of zoological study, morphology, com- 

 parative anatomy, ontogeny, etc. The body of 

 the book proceeds under two general heads — 

 ' The History of Zoology ' and ' General ■ Mor- 

 phology and Physiology.' The former covers 

 sixty-seven pages in which are presented with 

 surprising satisfaction and impartiality the posi- 

 tions of the creators of the science from the sys- 

 tematists and anatomists of classic antiquity to 

 the investigators and teachers of to-day. Two- 

 thirds of this space is justly given to the theory 

 of descent, its histoi-y and proofs. Lamarckian- 

 ism and Darwinism are succinctly interpreted 

 and the additions and modifications suggested 

 by advocates and opponents stated. In the 

 general morphological part after certain defi- 

 nitions are given comes the history of the cell 

 and the general principles of cytology ; the lat- 

 ter and the chapter on general embryology are 

 perhaps the most helpful in the book and leave 

 little to be desired in a summary of these sub- 



jects. If one wants to know the position of 

 zoologists on mimicry, distribution, promor- 

 phology, or the nature of species, this modest 

 manual will afford him a reliable exposition. 



The translator certainly deserves much credit 

 for his part, scarcely an involved or muddy 

 sentence occurs. The illustrations are familiar 

 but well selected. 



One so disposed might make a case in apparent 

 criticism, for example, the young sponge figured 

 on page 159, named ' Spongilla fluviatilis (after 

 Huxley),' some would prefer to see as Meyenia 

 fluviatilis (after Lieberkiihn) ; again on page 199: 

 " Many Protozoa fuse with one another and 

 form large bodies in which the individual ani- 

 mals can still be recognized." This seems to 

 imply more than some feel like granting. 

 Ophrydium versatile and Proterospongia haeckeli, 

 for example, occur in large masses with hun- 

 dreds of individuals imbedded in the support of 

 cast-ofi" or accumulated matter for protection ; 

 it seems to mean no more than the compound 

 pedicels of other forms, or a chain of the loricse 

 of Cothurnia variabilis. But such differences 

 may not be criticisms and certainly do not de- 

 tract from the usefulness of the book. 



Surely all who read this treatise will earn- 

 estly hope that the systematic part of the 

 ' Lehrbuch ' may speedily follow in the same 

 admirable style. D. S. Kellicott. 



Ohio State University. 



Lehrbuch der vergleichenden mikroskopischen An- 

 atomie der Wirbelthiere. Ds. Med. Albert 

 Oppel. Erster Theil ; Der Magen. Jena, 

 Gustav Fischer. 1896. 



Since Ley dig's ' Histologic ' appeared forty 

 years ago there has been no systematic attempt 

 at a summary of our histological knowledge. 

 The works on histology have confined them- 

 selves chiefly to the histology of man and the 

 higher animals, except in cases where a lower 

 form happened to be especially favorable for 

 purposes of illustration. The study of histology 

 has been so closely connected with that of 

 medicine that this is not to be wondered at; 

 but now, when the value of comparative study 

 is so obvious, and when the lower animals are 

 being studied from a purely scientific point of 

 view, an attempt to collate and arrange the 



