7 02 



THE POPULAR SCIENCE MONTHLY. 



LITEEARY NOTICES. 



VERTEBRATE EMBRYOLOGY. A TEXT-BOOK FOR 

 STUDENTS AND PRACTITIONERS. By A. 

 MILNES MARSHALL, M. D., D. So., Profess- 

 or in the Victoria University, etc. New 

 York: G. P. Putnam's Sons. London: 

 Smith, Elder & Co., 1893. Price, $6. 



As the author truly states in his preface, 

 most of the text-books of embryology aim 

 rather at explaining the general progress of 

 development within the several animal groups 

 than at supplying complete descriptions of 

 individual examples. Thus there have been 

 no reasonably complete accounts of the de- 

 velopment of the common frog or of the rab- 

 bit, while in human embryology so much 

 is yet unknown that the descriptions and 

 figures given in illustration of them are 

 those of embryonic rabbits, pigs, chickens, 

 or dogfish. As the results of recent investi- 

 gations have shown that marked differences, 

 both in the earlier and the later stages of de- 

 velopment, may occur between allied genera 

 and species, it may be perceived that this 

 practice of illustrating human embryology 

 by embryological types selected from the 

 lower animals may be the cause of much 

 confusion. 



In preparing this volume the author has 

 selected a few types to each of which a sepa- 

 rate chapter is devoted. The first chapter 

 gives a general account of the development 

 of animals, including the structure, matura- 

 tion, and fertilization of the egg, and a de- 

 scription of the early stages of the develop- 

 ment of the embryo. We think the author 

 has made a slight lapsus calami in the state- 

 ment on page 13 that " after one spermato- 

 zoon has entered an egg others seem inca- 

 pable of making their way in " ; we judge 

 that he intended to write " yolk " instead of 

 egg, for spermatozoa have been found not only 

 in the zona but in the perivitelline space. 

 We believe that it is after the spermatozoon 

 gains entrance into the yolk instead of the 

 egg, as is stated, that the tail is lost. The 

 theory of sex is too meagerly presented to 

 afford the student any enlightenment, none 

 of the more important theories being men- 

 tioned. 



The second chapter is devoted to the 

 amphioxus, giving a general account of the 

 early and late embryonic development of 



this fish-like animal. In this chapter the 

 author has followed the descriptions of 

 Kowalevsky, Hatschek, Lankester, and Wil- 

 ley ; and this animal has been selected as an 

 introduction to vertebrate embryology be- 

 cause of the simplicity of its earlier develop- 

 mental history as well as on account of the 

 clew that this affords to the more compli- 

 cated conditions occurring in the higher ver- 

 tebrates. 



The third chapter gives a general account 

 of the development of the frog, the descrip- 

 tion of the processes of maturation and 

 fertilization of the egg being based on 0. 

 Schultze's investigations, while the account 

 of the early stages of development of the 

 nervous, circulatory, digestive, and repro- 

 ductive organs is based on the observations 

 of the author and his pupils. 



The fourth chapter gives a description of 

 the development of the chick that is so fa- 

 miliar from the accounts given in most of the 

 physiologies. 



The fifth chapter gives an account of the 

 development of the rabbit, the author follow- 

 ing the accounts of Van Beneden, Kolliker, 

 and Duval in his description of the processes 

 of segmentation of the egg, of the formation 

 of the blastodermic vesicle, and of the pla- 

 centa. The descriptions of the later stages 

 of development are based on his own obser- 

 vations. 



The sixth and final chapter describes the 

 development of the human embryo, and is, 

 of course, to a large extent, based on the re- 

 searches of His. 



The author requests that human embryos 

 of any age, but more particularly those of 

 the first month or six weeks, be wrapped in 

 cotton, placed in a bottle of strong alcohol, 

 and sent to him at Owens College. 



We note, especially in the earlier part 

 of the book, a duplication of illustrations: 

 thus Figures 1 and 45 ; 2 and 14 ; 3 and 46, 

 47, 48, 49, and 50 ; 4 and 97 ; 5 and 102 ; 

 6 and 103 ; 7 and 105 ; 8 and 25 ; and 9 and 

 26, are identical. 



The book is clearly written in English 

 rather than Anglicized German, and there is 

 a most agreeable omission of German terms 

 that mar the harmony of some of the recent 

 works on embryology. Long quotations and 

 discussions of mooted points are avoided, the 

 author apparently seeking to present that 



