1907] 
FOUR USEFUL HOOKS 
87 
FOl’H rSEFFL HOOKS. 
Tiik iiicira.sinir and wclciniie dill'eri'iitiation lictwccn iiiaiiiials for the idcntifi- 
cati{)n of insects on the one hand, and text-hooks for llie study of entoinoloi;y on the 
other, has already led many an ainatenr entomolojiist to seek a lietter ae(iuaintanee 
witli hioloifieal lit<'ratnre in General; and f;ainin<; it, to find new sijfiiifieanee iti the 
common |)henomena of insect life which he has heen stndyin};. Kiitomologists are 
more and more coming to he hioloj;ists. 
Dr. Folsom’s “ Fntomoloey,”' puhlished more than a year a<;o, is an ailmirahle 
treatise on insect life in its hiolojj;ieal as|)eets. d'o students reniolt' from the lar^iw 
lihraries it hrines a masterly snmmary of a widely scattered literature. Its chapter 
oil Auatoniy and Fhvsiolo<ry is full of valuahle ideas for teachers, to whom the quality 
of the illustratimis must jiartieularly commend the hook. Its very fair-minded pre.s- 
imtation of the vexed suhjeet of .Vdaptive Coloration will abate the prejuiliees and 
perhaps inqu-ove the judgment of those who ailventure upon this tempting cround. 
'I'he treatment of the inter-relations of insects and plants is so flood that one wishes 
it were mueh more extensive. 'File fifty-eight jiages of hihliogra])hy at the end of 
the volume would a'lone entitle it to a place in every entomologist's library. 
'File hook contains few errors. .V very obvious one is in the statement of the 
approximate unmher of species of Coleojitera, on ]>age IS. 
Frofe.ssor Metcalf’s “(trganic Evolution,”' now in its second edition, is a very 
useful synopsis of eurfent evolutionary theory. It is interesting to note how largely 
entomology has contributed to the evidence here brought together, though we may 
jicrhaps demur a little at the space given to those time-honored but dubious exani|)les 
of “terrifying attitudes” furnished by the r>epidopfera. 'Fhe author’s own faith in 
them is not declared, but the jiietures give them undue promineiiee. On the whole, 
however, the book is well-balanced, and should .save its readers from some of those 
hasty interpretations of ob.served phenomena to which beginners are so prone. 
'Fhe experimental work of Fischer, Staudfuss, Fictet, Cuenot, (iralin von Lin- 
den, Fonlton, Cram])ton and many other investigators is eonci.sely summarized, with 
admiralile illu.stratious, in Professor Morgan’s “Experimental Zoology.”^ 'Fhe 
* Entomolojcy, with special reference to its biolo^jical and economic aspects. By Justus Watson Fol- 
som, Sc. I)., Instructor in Entomoloi^^v in the Ihuversity of Illinois. Philadelphia: P. Blakiston's Son Co. 
- An Outline of the Theory of Organic Evolution, with a dei?cription of some of the plienomena which 
it explains. By Maynard M. .Metcalf, Ph. I)., Professor of Bioh)gy in the Woman’s College of Baltimore. 
Second edition, revised. New York: The .Macmillan Co. 
3 Experimental Zoology. By Thomas Hunt Morgan, Professor of Experimental Zoology in Columbia 
University. New York: The Macmillan Co. 
