IN a notice of vol. i. of the above work (NATURE, vol. xlii. p. 244), its object and scope were explained. Vol. ii., now before us, fully justifies what was there stated as to the thoroughness with which the available materials on the subject have been brought together from all sources, and for the first time presented to the world as a whole. A similar popular treatment also of this interesting and most important part of the subject is again here observable. Vol. i. was occupied with the snares and web-spinning of orb-weaving and some other spiders, principally in relation to the getting of their livelihood. Vol. ii. treats of these spiders in respect to the propagation of their kind, and web-spinning as subservient to this. Vol. i., in fact, presents us with spiders safely arrived at maturity, and forming their snares and webs with all the diversity and perfection peculiar to each species; while vol. ii. takes them up at that point, and shows them to us in all the different peculiarities pertaining to the performance of the ultimate object of their existence. Naturally, therefore, the volume before us begins (part i., chapter i.), with an account of the sexes in their relation to each other preparatory to actual pairing. This latter and the points arising out of it form the staple of chapters ii. and iii., which complete part i. A certain air of sentimental allusion, which appears to pervade the author's method of presenting this part of his subject, is perhaps merely a matter of taste, and so beyond the province of scientific criticism. It may be, however, that this, while it certainly adds nothing to scientific accuracy or progress, does add to the popularity of the subject, which is evidently throughout the work one of its author's great objects. On the small size of many male spiders compared with their bulky females, Dr. McCook does not appear to accept the views of a former writer upon it, in which it should be observed that the primitive equality in the size of the sexes is by no means implied; the general rule being that the male is the smaller of the two. But if it be granted that the female had a propensity for attacking and devouring the male, those males which happened to be the smallest and most active would be the most likely to escape, and perform the functions of the sex; natural selection would then come in, and operate gradually in the direction of lessening the size of the males. That there are numerous spiders, and groups of spiders, in which the sexes are nearly equal in size, or live in amity together, or in which the males are furnished with some protective armature against the ferocity of the female, proves nothing against the theory of the action of natural selection in lessening the size of the male in such cases as those where a devouring propensity existed and was otherwise unprovided against; for in groups where any approach to equality in size existed and became protective, or where some other protection became developed, there would be no need, in fact no case, for natural selection in the direction of diminished size, there being no advantage to be gained under it. The drift, however, of the author's reasoning on this subject (p. 7) is not very apparent.
American Spiders and their Spinning Work: a Natural History of the Orb-weaving Spiders of the United States, with Special Regard to their Industry and Habits.
By Henry C. McCook Vol. II. pp. 1–479, with 5 Coloured Plates and 401 Woodcut Figures. (Philadelphia: Allen Lane and Scott, 1890.)