98 
INA TO AE: 
[ DECEMBER 3, 1903 
proof of which fact is furnished by the liberty which 
each of these excellent works takes with Euclid’s Prop. 
19, Bk. vi.—‘ similar triangles are to one another in 
the duplicate ratio of their homologous sides ’’— 
mysterious but high-sounding to countless generations 
of schoolboys. Here it is, in identical words in both 
books, ‘‘ the ratio of the areas of similar triangles, or 
of two similar polygons, is equal to the ratio of the 
squares on corresponding sides,’’ brought down to 
definiteness and intelligibility at last! 
There are certain time-honoured propositions in the 
treatment of which teachers will tale a special interest, 
and none more prominent than Euclid’s Prop. 1 of 
Bk. vi. Messrs. Barnard and Child prove it by 
assuming that the bases of the triangles are multiples 
of some common length, while Messrs. Godfrey and 
Siddons (p. 175) treat it as a mere result of the fact that 
the area of a triangle is half the product of a base and | 
the corresponding perpendicular—both proofs, of 
course, resting on the same ultimate assumption. In 
justification of such proofs it may be said that no useful 
purpose will be effected by an early discussion of in- 
commensurable quantities. 
There are many things—such, for example, as the 
constancy of the product of the radii vectores from a 
fixed point to a circle, the nature of a tangent as a 
limiting position of a chord, &c.—in which we have an 
agreeable and useful variety of treatment in these two 
works, but the limitation of space renders further 
reference to them here impossible. 
G. M. Mrincuin. 
“ SEMI-DAR WINIAN ” 
Doubts about Darwinism. By a Semi-Darwinian. 
Pp. vit115. (London: Longmans, Green and Co., 
1903.) Price 3s. 6d. 
SPECULATIONS. 
HE preface of this work informs us that its author 
has endeavoured to conform strictly to the prin- 
ciple laid down by Lord Kelvin, as follows :—‘‘ If a 
probable solution, consistent with the ordinary course 
of nature, can be found, we must not invoke an 
abnormal act of Creative Power.’’ Unfortunately the 
“* Semi-Darwinian’s ’’ practice is not in accord with 
his profession. Whenever he meets with a problem in 
evolution which appears to him inexplicable on the 
lines of natural selection, so far from seeking for ‘‘a 
probable solution, consistent with the ordinary course 
of nature,’’ he resorts at once to the intervention, by 
a direct creative act, of ‘‘a Being possessing intelli- 
gence, intention and power.’’ This is bad science, and 
we much doubt whether it is good theology. 
Opinions have differed, and will doubtless for a long 
time continue to differ, as to the extent of the influence | 
of natural selection as a factor in evolution. | Darwin 
himself, as is well known, thought that its operation 
might be supplemented by that of the factors adduced 
by Buffon and Lamarck. Whether in view of the in- 
crease of knowledge since Darwin’s day, and of the 
numerous cases of difficulty which have lately been 
satisfactorily explained on the basis of natural selec- 
tion, he would have been led to discard those hypo- 
theses that involve the hereditary transmission of 
NO. 1779, VOL. 69] 
| quotes Romanes’s 
| investigation of the facts, but appears to be quite un- 
acquired characters, it is, of course, impossible to 
say. But it certainly seems probable to those workers 
in whom the Darwinian tradition is strongest that 
their leader,-were he living now, would attribute more 
rather than less importance to his distinctive principle 
of natural selection. However this may be, the fact 
remains that if by ‘‘ Darwinism ’’ be meant the natural 
selection of ‘‘ accidental ’’ variations, the doubt as to 
its claim to be the sole factor in evolution is a doubt 
that was felt by Darwin himself. Hence we demur to 
the title of the present work. 
A matter of greater importance is the author’s 
attempted demonstration of the impossibility of ex- 
plaining certain phenomena on Darwinian principles. 
It is true that some of the facts he adduces have been 
felt as difficulties, but not, as a rule, in the way that 
he supposes. To answer his objections point by point 
would be lost labour, for he shows on almost every 
| page that he is unacquainted with the conditions of 
the problem. His remarks on the subject of vision, of 
reproduction, of embryolovy, to take a few instances, 
are those of a disputant who has entered the lists with- 
out the necessary equipment. Argument with such an 
opponent is unprofitable. As an example of the failure 
of the ‘‘ Semi-Darwinian ”’ to master the present-day 
aspects of the subject, we may take his treatment of 
the caterpillar and beetle-stabbing instincts of Sphex 
and some other genera 0° fossorial Hymenoptera. He 
expression of a desire for further 
aware that the need has been to a great extent sup- 
plied by the labours of two industrious and accurate® 
naturalists in America, who have put an entirely new 
complexion on the case as it was known to Darwin. 
We have no wish to detract from the merits of so 
| zealous and patient an observer as Fabre, to whose 
| writings those who have discussed the habits of Sphex, 
Ammophila, and their allies have generally been in- 
debted for their facts; but it is impossible to study the 
recent work on the subject without recognising that 
Fabre’s inferences are sometimes unwarranted. Even 
before the new facts had been brought forward by 
G. and E. Peckham, the difficulties of explanation on 
the lines of natural selection, though great, did not 
seem insuperable; they may now be said to have dis- 
appeared. 
But it is not only on such points of detail as the 
foregoing that the author shows his absence of qualifi- 
cation for dealing with the modern phases of the 
evolutionary problem. To say nothing of other 
omissions, the whole series of considerations specially 
associated with the names of Baldwin, Lloyd Morgan. 
and Osborn is entirely ignored by him, nor does he 
give any sign of being acquainted with recent views 
on the subject of heredity. In short, as an attack on 
the adequacy of natural selection, his book, besides 
being ineffective, is hopelessly belated. 
Supposing,» however, that the author’s strictures 
were well founded; that he had really contrived to 
point out certain stages in the evolutionary process 
which are not, and apparently never can be, explained 
on the basis of natural selection—what then? Surely 
in accordance with his own canon his next step should 
be to search for some other natural cause of the 
