28 



SCIENCE. 



[N. S. Vol. III. No. 53. 



tral form to develop in that direction. Again a 

 difficulty is encountered when we examine an- 

 otlier of our author's fundamental principles, 

 the inheritance of acquired characteristics, be- 

 cause the assertion of this principle is made and 

 yet no demonstration of its truth is offered — it 

 is at best a bold hypothesis. 



Another peculiarity of the author's position 

 is his serious misapprehension of Darwin's 

 theory, which he mistakes repeatedly. He re- 

 jects Darwinism because it does not explain the 

 origin of variations. Darwin, of course, did not 

 attempt to more than suggest certain explana- 

 tions, and his theory of natural selection does 

 not depend on the origin of variations, but on 

 the demonstrated fact that innumerable varia- 

 tions do occur and numerous variations have 

 been transmitted. Prof. Eimer claims that his 

 book should be ' read and studied, ' in return we 

 claim that before he again writes against Dar- 

 win, he should thoroughly master Darwin's 

 chief work, the ' Variation of Animals and 

 Plants.'' Until he has done that his attacks 

 must remain unheeded, for they are only 

 against a straw substitute for Darwinism. 



Professor Elmer's book is a valuable contribu- 

 tion to descriptive entomology, and sets before 

 entomologists a high standard of description and 

 illustration of species. It is also an unsuccess- 

 ful attempt to substitute for Darwinism a new 

 theory of evolution, based wholly upon hj'po- 

 thetical assumptions, for no one of which is sub- 

 stantial proof offered, and so far from agreeing 

 to the author's claim that his theory is a series 

 of facts, we must, on the contrary, say that it is 

 a collection of arbitrary assertions. He con- 

 demns Weismann very emphatically for specu- 

 lating, and yet shows himself, perhaps, the 

 more speculative of the two. 



C. S. MiNOT. 



The Structure and Life of Birds. By F. W. 



Headley, M. a., p. Z. S. London, Mac- 



millan & Co. 1895. 8vo. Pp. sx. 412. 



78 illustrations. $2.00. 



This book ' ' attempts to give good evideuce 

 of the development of birds from reptilian an- 

 cestors, to show that modifications in their an- 

 atomy have accompanied their advance to a 

 more vigorous life, and, after explaining, as far 



as possible their physiology, to make clear the 

 main principles of their noble accomplishment, 

 flight, the visible proof and expression of their 

 high vitality. After this it deals, principally, 

 with the subjects of color and song, instinct and 

 reason, migration and the principles of classifi- 

 cation, and, lastly, gives some hints as to the 

 best methods of studying birds." 



Mr. Headley's aim is confessedly an ambitious 

 one, and since he has shot so well he must not 

 take it amiss if he is told that his pen has not 

 carried quite true throughout its entire flight. 

 It is difficult to compress so many subjects as 

 are contained in the ' Structure and Life of 

 Birds ' into the compass of four hundred pages, 

 and we can not expect to have every point 

 touched on fully and clearly explained. Still, 

 making due allowance for this and for the pop- 

 ular audience to which the book is largely ad- 

 dressed, there is a certain amount of looseness, 

 or inexactness, of statement that might have 

 been avoided. For example, uncinate processes 

 are not ' common to all birds, ' since they are 

 absent in the Screamers, a fact which might 

 have been explained in half a dozen words. 

 Neither is the supplementary toe of the Dorking 

 Fowl a dermal bone, but a case of duplication 

 of a digit, the perpetuation by careful breeding of 

 an abnormality now and then seen among ani- 

 mals, even in man. This looseness of diction 

 is well shown by the constant reference to bones 

 filled with marrow as solid bones ; and the state- 

 ment that the coracoid and clavicles are firmly 

 fixed to the breast bone, when this is rarely the 

 case ; and those birds in which the clavicle is 

 most securely fastened to the sternum are by no 

 means among our best birds of flight. The 

 statement that all the bones of the Swallow are 

 filled with marrow is a little indefinite, and if 

 intended as generalization, misleading, since the 

 humerus may be pneumatic, even among Swal- 

 lows. 



However, pneumaticity is a very inconstant 

 character and is not even of generic value. 

 The connection between the reduced phalanges 

 of the Swift and its alleged inability to rise from 

 the ground is not clear to the average mind, 

 and it is rather startling to be told that the 

 Rook may be told from the Crow by the absence 

 of feathers on the beak. 



