NOTICES OF NEW BOOKS. 243 



evolution; he is more concerned with the appearance of the 

 living form than with its structure ; but he is, nevertheless, not 

 seldom, a master of his craft. The value of his observations was 

 appraised and canonized by Darwin ; but that it should be less 

 superficial, that it should be more introspective, have a wider 

 meaning, and a more philosophical clue, is unquestionable, and 

 a book like this supplies the one thing needful. Zoology can 

 neither be divorced from the fields nor from the laboratory — it is 

 part and parcel of our own history ; in an evolutionary sense 

 14 our birth is but a sleep and a forgetting " ; and even the Echi- 

 noderma, when thus described, and the inseparable technicalities 

 absorbed by the ready mother wit of both student and peasant, 

 will increase our knowledge of what they are, and our perception 

 of what we are. 



There is a most excellent bibliography attached to each 

 branch of the subject ; and the book is far more than a 

 zoological ledger posted up to date. 



Sexual Dimorphism in the Animal Kingdom: a Theory of the 

 Evolution of Secondary Sexual Characters. By J. T. 

 Cunningham, M.A. Adam and Charles Black. 



Most naturalists are familiar with Darwin's theory of " Sexual 

 Selection," a theory which perhaps met with less general accept- 

 ance than any other put forward by our great biological philo- 

 sopher, being even vigorously opposed by Mr. Wallace, his 

 fellow-enunciator of the doctrine of " Natural Selection." Mr. 

 Cunningham not only offers another hypothesis, but altogether 

 starts from a Lamarckian standpoint, and is quite outside the 

 views of either Darwin or Wallace on the subject, frankly stating 

 that his object is to point out "how remarkably the multitudinous 

 facts all agree with the hypothesis that secondary sexual characters 

 are due to the inheritance of acquired characters." This course 

 leads the author to some most startling speculations. His con- 

 clusion being " that the direct effects of regularly recurrent 

 stimulations are sooner or later developed by heredity, but only 

 in association with the physiological conditions under which they 

 were originally produced," we meet with the following suggestions 

 as to the origin of the beard in males, which "it is probable 



