674 



THE AMERICAN NATURALIST. [Vol. XXXV] II. 



what larger at one end than at the other" (p. 90). (If the egg of 

 the " chick " were not ovoid, what would its form be ? ) Then follows 

 what apparently is a description of the egg at the time of laying. In 

 the course of this description it is stated that the yolk exhibits on 

 one side "a small, whitish circle, the blastoderm ox cicatricula " (p. 91). 

 The next paragraph tells us that " Although of so large a size, the 

 yolk of the hen's egg is a single cell, its great size being chiefly due 

 to the large number of yolk granules which it contains "(p. 92). 

 Fortunately, the last paragraph of the section on "The Egg" explains, 

 as if by an afterthought, that " The preceding is a description of the 

 egg at the time of its laying" and that "The statement that the yolk 

 IS a single cell is really true only from the time it leaves the ovary 

 until it is fertilized, or until a short time after fertilization, when seg- 

 mentation begins " (p. 93). Even then we are left in doubt as to the 

 precise time when the egg ceases to be a single cell. It does not 

 tend toward conciseness to make an incorrect statement and then 

 add a paragraph to explain what is "really true " 



In the accounts of the visceral apparatus of both frog and chick, 

 an md.scriminate use of the terms gill branchial, and visceral, as 

 applied to the several arches and clefts, leads to hopeless confusion. 

 It IS doubtless by an oversight that the author states that the ecto- 

 ermal auditory invagination of the frog gives rise to the lining of 

 the middle ear (p. 43). it is a surprise to find the i^xvus somato- 

 phMrc and splanchnopieure applied to the parietal and visceral layers 

 Ucu'k^'^'''"' ,'^'P'^''^^''^^>'- ^^^he use of the incorrect plurals "diver- 

 tieu X and liimena," an apparent failure to appreciate that //t/m 

 P 111 a , and reference to nascent organs as rudiments are com- 

 Piiratively iin important matters. The figures, mainly from Marshall, 

 uva , and Minot, are well reproduced, but their arrangement in rela- 

 tion to the text could be much more convenient. 



A book such as Dr. Reese has proposed should lay down in a few 

 m bold strokes the main outlines of the subject. Unimportant 

 treated t'''^ ""P^^^^"^ ^^t^''^ ^^^^t be adequately 



al Jn!«\>^J^? ^account must proceed in an orderly constructive way. 



as it has progressed, like the developniem 

 ' such unfailing accuracy and such clearness 

 iT ^"^^"^^"^ ^^^^ misconception is impossible. If Dr. Reese's book 

 v.r ''"^"''^'ified success, it is because the author undertook a 



^ery difficult task. 



H. VV. R. 



There 



