IC)0 Recent Literature. I A p r ;i 



express an opinion on the question at issue, or his proneness to give rein 

 to his fancy on slight provocation. It is obvious that a -wrong theory is 

 worse than no theory; for to the lay reader or half-informed student who 

 is unable to discriminate properly between the probable and the improb- 

 able, it is sure to be positively misleading. Pure speculation is the bane 

 of science; it misguides the uninitiated and disgusts the well-informed. 

 Many writers more gifted with imagination than with knowledge have 

 contributed largely to romance under the guise of science, and especially 

 is this the case in the particular field which includes such topics as Mr. 

 Keeler here treats. 



We do not wish this to be construed, however, as a wholesale condemna- 

 tion of Mr. Keeler, or of theorizing in general; on the contrary we find 

 much to commend in Mr. Keeler, and recognize the absolute necessity of 

 hypotheses in scientific research; we wish merely to emphasize the fact 

 that there is much natural history romancing which has wide currency as 

 'science.' A fair acquaintance with current theories respecting a few 

 special phases of the subject of evolution, a merely superficial 

 knowledge of the underlying principles, and a vast ignorance of the facts, 

 of biology at large, is too apt to form the equipment and the incentive of 

 some of our boldest theorists in the field of speculative biology, for 

 whom nature has no secrets beyond their power to explain. This, 

 indeed, is our estimate of much of the speculative writings of Poulton, 

 Romanes, Weismann, and many other writers who have of late been so 

 prolific of explanations of the abstruse things in nature, whom Mr. 

 Keeler so freely quotes, and whom he has evidently taken as his models. 

 He has, however, shown in general less discretion and more recklessness 

 in his conclusions and generalizations. 



Mr. Keeler's work consists of two paj'ts, an 'Introduction,' occupying 

 the first 132 pages, the remainder being devoted to 'The Colors of North 

 American Birds' (pp. 132-336). Then follows a bibliography, explana- 

 tions of plates, and an excellent index. The first part treats of gen- 

 eral questions, such as 'The Inheritance of Acquired Characters' (pp. 

 2-50), 'Variation and Natural Selection' (pp. 50-63), 'Laws conditioning 

 Evolution' (pp. 64-S0), 'Sexual Selection' (pp. So-102), 'The Nature of 

 Species' (pp. 103-109), and 'Isolation as a Factor in the Evolution of 

 Species' (pp. 110-132). 



As Mr. Keeler says, in view of the disagreement between the leading 

 writers of the different schools, "it is quite impossible to undertake any 

 general scientific investigation in the field of evolution without a toler- 

 able survey of the whole ground." As he further says : "There is hardly 

 one of the important doctrines concerning which a consensus of scien- 

 tific opinion has been attained. To be sure, all maintain that Darwinism 

 or natural selection is a factor in evolution, but while some hold it to 

 be the only factor, and all-sufficient in the creation of species, others 

 believe it to be a very minor agency, and relegate it to the post of 

 inspector-general of the army of life. With regard to sexual selection the 



