376 EXPERIMENT STATION RECORD. 



Experimental embryolog-y, J. W. Jenkinson {Oxford, J 909, pp. TIII+S'il, 

 figs. 167). — This volume attempts to sketch the progress of researches on cell 

 division, growth, tlift'erentiatiou, and the external conditions that influence the 

 development of the organism. The data submitted on cell division is taken 

 chiefly from experiments of invertebrates and that on growth from measure- 

 ments and weights of mammals. 



A summary of experimental investigations up to the present time indicates 

 that the internal factors governing development are the initial structure of 

 the germ and the mutual relations of its parts, and that normal development 

 is necessarily conditioned by the physical and chemical environment. 



" Development then proceeds from the comparatively simple organization 

 given in the structure of the fertilized ovum by the creation of ever-increasing 

 complexity by the action and reaction of the parts on one another. Each 

 ontogenetic effect produced becomes in tui'n the cause of further effects, the 

 possibility of fresh specific action, for it becomes the seat of a new specific 

 stimulus and response, and so on until the complexity of the ' ultimate oi-gans ' 

 of the adult is achieved. 



" In order, however, that differentiation may be normal it is clear that these 

 stimuli and these responses must be accurately coordinated : the right stimulus 

 nnist be ready at the right time and at the right place for the right organ to 

 respond to." 



The author points out that the development of every organ must be examined 

 in detail by experimental methods. Although in general the views of Driesch 

 concerning the development are endorsed, the author repudiates the doctrine of 

 neovitalism, which postulates an immaterial entity to guide the merely me- 

 chanical forces toward the realization of the "end" to be attained in every 

 organic ])rocess. 



A bibliograi)hy is ap])ended to each chapter. 



Text-book of embryology, F. R. Bailey and A. M. Miller {Xcw York, 1909, 

 pp. XIV— G72, figs. 515). — This is an extensive summary of investigations of 

 cell and cell division, formation of the sexual elements, and development of 

 the fetus and fetal membranes. Although written primarily for students of 

 medicine, the development of the growing organism is treated from the com- 

 parative standpoint for those who are interested in the embryology of mammals. 

 Directions are given for the study of amphibian, chick, and mammalian 

 embryos. 



A bibliography is ajipended to each chapter. 



Heredity, W. E. Castle {Pop. 8ci. Mo., 77 {1910), No. 5, pp. /,17-.',28, figs. 

 13; Sci. Amcr. Sup., 69 {1910), Xo. 1797, pp. 369, 376, 377. figs. 7.^).— Experi- 

 ments of the author in breeding guinea pigs are used to illustrate the funda- 

 mental principles of (1) singleness of the germ in contrast to the duality of the 

 individual; (2) blending inheritance; (.3) Mendel's law of discontinuous inherit- 

 ance. The view is advanced that notwithstanding the seemingly radical differ- 

 ences between blending and discontinuous inheritance, they may prove to have 

 a common basis and that future experiments may show blending inheritance to 

 be a form of Mendelian inheritance, in which many independent factors are 

 concerned. 



Some modern views concerning' heredity and variation, R. H. Firth {Jour. 

 Roy. Army Med. Corps, 13 {1909): No. 6, pp. 633-61,6, figs. 3).— This is an 

 address before the Aldershot Military Medical Society, November, 1!»00. and 

 ]»resents in a popular form the principal facts known concerning heredity. The 

 advantages of obtaining accurate data on the inheritance of congenital defects 

 and abnormality are pointed out. 



