342 NATURAL SCIENCE. May. 



lightened the rest of the skull b}' over 5 per cent, in the fifty speci- 

 mens (mainly Italian) which I weighed. Whatever estimate may be 

 formed of the remaining portion of the reduction in the European jaw, 

 we still have to deduct the effect of disuse during lifetime and the 

 direct or transferred effect of sexual and social selection in repressing 

 prognathism. What grounds can we have for assuming that any 

 residue remains which can justly be claimed as a proof of the 

 inheritance of the effects of ancestral disuse ? ^'^ 



In endeavouring to establish the inadequacy of Natural Selection, 

 Mr. Spencer puts forth contentions or assertions which manifestly 

 overpass the bounds of accurate and logical reasoning. He holds, for 

 instance, that if Natural Selection does not cause ^'- a. frequent snrvi- 

 val " of individuals possessing any particular trait, it can " neither 

 cause nor aid " any change in that direction. But surely it is as 

 rigidly inevitable as any arithmetical or mathematical fact that the 

 occasional elimination of an unfavourable characteristic must propor- 

 tionally affect the general average. Nay, the elimination of a single 

 individual thus characterised has, ipso facto, altered the average among 

 the survivors. There is not the least reason, therefore, for accepting 

 the strangely unphilosophical dictum that an evolutional cause or 

 factor will not act at all unless it acts in considerable or important 

 degrees. We may safely allow science and reason to implant in us a 

 perfectly firm and unwavering conviction that every cause, however 

 weak, will produce its proportional effect ; and we may expect that 

 the long-continued and cumulative effect of even infinitesimal forces 

 or tendencies may become perceptible in the course of sufficient time. 



** Mr. Spencer has unintentionally exaggerated the extent of the diminution. A 

 comparison of his statements {Principles of Biology, % 166, footnote) with the skulls 

 which he inspected at the College of Surgeons will prove to any careful measurer 

 that the jaw, which was too hastily assumed to be " an average English jaw," must 

 actually have been the smallest English jaw in the collection — that, namely of a 

 female skeleton (No. 70A) with exceptionally delicate features. Founded on such a 

 basis, his ideas and statements concerning the " dwindling away " of the jaw go far 

 beyond the sober facts. As Mr. Spencer's disciples thus learn to overrate the decrease 

 of the jaw, so also they become apt to underrate the reducing causes. Thus Mr. F. H. 

 Collins (compiler of " An Epitome of the Synthetic Philosophy," an abstract of Mr. 

 Spencer's works and teachings, published with an approving preface from the hand of 

 the master himself) represents the amount of nutriment required by the whole jaw 

 as a grain a day and calls this " a large estimate " {The Diminution of the jfii'tu in the 

 Civilised Kaces an Effect of Disuse, p. 12). A little arithmetic will show that the pro- 

 portional share of daily nutriment for the jaws with their muscles, &c., is some sixty 

 times greater than this, without including liquid. Master and pupil alike seriously 

 underrate the extent of variation, and ignore the facts that the reduction in the 

 jaw is largely correlated with a similar reduction in the skull as a whole, and that 

 the reduction of weight to be moved would allow a proportional economy in the 

 bones and muscles and limbs and body that carry the lightened head with its 

 lightened jaw ; and all this allows still further and complicatedly cumulative economy 

 in the alimentary, circulatory, respiratory, and food-procuring organs, which only 

 have to provide a lessened amount of duly prepared nutriment for the economised 

 parts. Arithmetically estimated, the case for economy is made to appear hundreds 

 of times weaker than a fair consideration of the relevant facts would justify. 



