780 



SCIENCE. 



[N. S. Vol. VII. No. 179. 



mentioned that a few of those plastic figures 

 are somewhat unclear, apparently due to a fail- 

 ure in the execution of the original drawing. 



The arrangement of the contents is very con- 

 venient. We find in the first part, according to 

 the generallj' accepted plan, the description of 

 the ovum, maturation, fertilization, cleavage, 

 formation of the germlayers and the fundamen- 

 tal processes in development of the embryonic 

 body, and finally the fcetal membranes. The 

 following chapter contains an exhaustive and 

 very useful account of the growth and external 

 development of the human fcetus, especially dur- 

 ing the first two months, together with some 

 data on measurement and the determination of 

 age. 



The second part of the book deals with the 

 development of the special organs. lu arranging 

 this material the author follows the customary 

 method of systematic anatomy, describing first 

 the development of the skeleton and the mus- 

 cular system, and then going on with that of 

 the intestinal tract, the circulatory apparatus, 

 the nervous system, and finally the skin and 

 the sensory organs. Such an arrangement has 

 many advantages and is obviously adapted 

 especially for medical students. Scattered 

 through the descriptive text we find also some 

 theoretical discussions which are usually 

 marked off from the main text by smaller type. 

 These discussions touch upon questions of 

 special interest for a better appreciation of 

 certain points in human ontogenesis. 



In criticising the treatment of the material 

 in Professor KoUmann's text-book one deficiency 

 in the reviewer's opinion seems to be rather 

 serious — that is, the almost absolute neglect of 

 the histological difl'erentiation of the tissues in 

 general as well as of the different organs, to- 

 gether with a lack of figures illustrating these 

 processes. These processes are not only of in- 

 terest for the professional embryologist, but also 

 to a high degree for the medical student, in so 

 far as an adequate knowledge of them is of 

 preeminent importance for a satisfactory un- 

 derstanding of so many phj'siological and path- 

 ological processes of the organs. Hence it 

 seems to the reviewer that in a modern text- 

 book of embryology this important part of 

 development should not be entirely omitted, 



all the more as recent investigations have 

 thrown more light upon these very com- 

 plicated processes, and as the field of cellular 

 embryology will be more and more cultivated. 

 These deficiencies, however, in KoUmann's 

 text-book do not interfere with its peculiar 

 excellence, which lies in the exact anatomical 

 treatment of the developing organism, together 

 with the elucidation of the text by numerous 

 very instructive illustrations. It is in this es- 

 pecially that the book forms a valuable addition 

 to our embryological literature and deserves to 

 be highly recommended. The different chap- 

 ters are in general well balanced. The text is 

 concise and clear. Print and reproduction of 

 illustrations are according to the high repu- 

 tation of the publisher. 



Alfred Schapee. 



A Primer of Psychology. By Edward Brad- 

 ford TiTCHENER. New York and London, 

 The Macmillan Co. 1898. Pp. xvi + 314, 

 Price, $1. 



As the scientific claims of psychology are 

 more widely recognized, there is an increasing 

 demand for elementary text-books on the sub- 

 ject. Professor Titchener has in mind the diffi- 

 culties of the beginner, and while there is more 

 science and less glitter in this Primer than is 

 common in courses of ' science made easy' it 

 can scarcely fail to interest the novice as well 

 as instruct him. The fundamental concepts are 

 defined with unusual clearness, and every difiS- 

 cult point, as soon as it comes up, is carefully 

 explained, often with the help of illustrations 

 taken from literature or the physical scieneese 

 The Primer is not intended primarily as a 

 course in experimental psychology. The body 

 of the text is rather analytic, although the chief 

 results of experimental research, such as 

 Weber's Law, are given much space. As 

 would be expected in a work by Professor 

 Titchener, the whole treatment of the subject is 

 largely influenced by this branch. Among the 

 many practical exercises found at the end of each 

 chapter, as much in the way of experimen- 

 tal demonstration is included as is practicable 

 for classes with only a limited supply of appa- 

 ratus at command. When on debated ground 

 the author generally adheres to the theories 



