203 
Species and other Controversial Points. 
appearance ; it simply kills out any that are really disadvantageous ; and 
that, it now appears clearly from my work on age and area, it does in the 
very early stages, when a species is represented by a few individuals only. 
The supporters of Natural Selection do not clearly distinguish between 
post hoc and propter hoc . Does Mr. Ridley imagine that the spines on one 
of the Metroxylons (p. 562) began by infinitesimal variation ? If so, did the 
infinitesimal spines make any difference to the survival of the species ? Had 
the pigs more delicate mouths in those days ? Or were there any pigs ? 
But if they did not begin in this way, where did Natural Selection come 
in ? The spines are suddenly produced, and being uninjurious, are not 
weeded out by Natural Selection, but Natural Selection did not produce 
them, and cannot be their explanation. The other species, with no spines, 
survives also. 
Does Mr. Ridley suggest that the Vitex on p. 564, which on being 
moved to Singapore proved to be V. trifolia , was a distinct species ? Did 
it refuse to cross with V. trifolia ? 
For many years I have kept a note-book in which I have noted down, 
under the various letters of the alphabet, various questions which may be 
proposed to the supporter of Natural Selection, and will quote, for Mr. 
Ridley to answer if he can, a few of those under A : 
How did the following commence, and what advantage was gained by 
the rudimentary beginning, sufficient to ensure the completion of the organ 
in question ? 
Phyllodes in Acacial 
Sensitive leaves in Aldrovandal 
Bulbils in many species of Asplenium ? 
Thorny roots in Acanthorhiza ? 
Simple, lobed, and compound leaves in different Acers ? 
Dehiscent berries in Akebia ? 
Reversed leaves in Alstroemeria ? 
The formation of adventitious embryos ? 
Hooked bracts in Arctium ? 
Cauliflory in some Artocarpus ? 
Scaly pappus in Achyrachaena ? 
Anisophylly in many plants ? 
Sympodia in A ncistrocladus ? 
Pollinia in Asclepiadaceae ? 
If these, or most of them, arose, as one must believe, directly at one opera- 
tion, where does Natural Selection come in as formative or explanatory ? As 
they are not harmful mutations it allows them to survive, but that is the end 
of its activities, so far as we can see. Natural Selection cannot be regarded 
as the formative agent for differences in individual species, as has been done 
