218 



SCIENCE 



N. S. Vol. XXX. No. 763 



lence and fidelity of Dr. Lillie's figures. The 

 last two sections of the chapter, describing the 

 mesoblast of the opaque area and the germ 

 wall, are very satisfactory. The chapter as a 

 whole is a good account of the origin of the 

 mesoderm. 



The fifth chapter, Head-fold to Twelve 

 Somites, is divided into parts upon the head- 

 fold, fore-gut, neural tube, mesoblast and an 

 embryo with ten somites. The attempt to de- 

 scribe the growing embryo, as a whole, breaks 

 down in this chapter, and it might have been 

 better to begin the part upon organogeny at 

 the end of this chapter or earlier instead of 

 after the next chapter. As it stands, portions 

 of this chapter and of the next anticipate 

 statements which are made later. 



The second part of the book contains, in 

 addition to chapters on each organ-system, a 

 chapter on the external form of the embryonic 

 membranes and one on the body cavities, 

 mesenteries and septum transversum. There 

 is an extensive and useful bibliography. 



The book contains the inevitable errors of a 

 first edition. There is no mention of the 

 origin of the feathers, of the Ijrmphatic ves- 

 sels and of the muscles of the eye. The an- 

 terior division of the embryonic heart is called 

 the bulbus arteriosus, or the bulbus, in the 

 text, index and the original figures, but is 

 named the ' bulbus cordis in copied figures. 

 The choroid fissure is said to provide " an 

 aperture in the wall of the optic cup for the 

 entrance of the arteria centralis retinae " (p. 

 166), but the author himself says elsewhere 

 " There is no arteria centralis retinae in the 

 bird's eye" (p. 281). Happily such slips are 

 infrequent. 



The book contains a large amount of new 

 material, for in addition to the second and 

 fourth chapters upon the development of the 

 egg before laying and upon the origin of the 

 mesoderm, which embody difficult and funda- 

 mental research, it makes many small contri- 

 butions to our knowledge of the embryology of 

 the chick. The value of the book is greatly 

 enhanced by this original matter, which, al- 

 though it usually serves only to decide between 

 conflicting opinions or to add small details, 

 and although in conformity with the purpose 



of the book discussion of the literature and of 

 interpretation is reduced to a minimum, gives 

 a great store of facts that will be constantly 

 referred to by students of embryology. 



The numerous figures are well chosen and 

 executed, but the publishers have poorly re- 

 produced a number of them. More than half 

 of the figures are new and among these are 

 some very excellent drawings of whole em- 

 bryos, and new diagrams of the structure of 

 the egg and of the embryonic membranes. 

 Some of the figures of sections could well be 

 replaced by drawings of models. 



The typography of the book is unusually 

 good. 



Professor Lillie's book, being a comprehen- 

 sive and accurate statement of the processes 

 by which the body and organs of a single 

 animal are formed, will be of great service in 

 the class-room where the careful observation 

 and correlation of phenomena giving a train- 

 ing in true scientific method, are of more value 

 than a broad and vague knowledge of many 

 things and theories. 



Leonard W. Williams 



A Canyon Voyage. By Frederick S. Dellen- 

 BAUGH. New York, Putuams. 1908. 50 

 plates. 



Major Powell's " Exploration of the Colo- 

 rado River of the West " is famous as a daring 

 enterprise of forty years ago. His first river 

 voyage in 1869 was briefly chronicled in his 

 official report of 1875, and described in a more 

 general manner in a popular book of later 

 issue. His second voyage through the canyon 

 in 1871 from the same starting point at Green 

 Eiver, has never been adequately described, 

 although the results of observations then made 

 were incorporated in the report above cited. 

 At this late date, Dellenbaugh, a member of 

 the second party, who has already written the 

 " Romance of the Colorado Eiver," in which 

 earlier explorations are described, now gives 

 us what he regards as a sequel to his previous 

 book, in the form of a minute narrative of the 

 second boat trip down the river, when he was 

 artist and assistant topographer of the party. 

 There is no attempt at scientific discussion, 

 but a faithful effort is made to record every 



