352 



not yet been able to spread further than one mountain peak, where it was first evolved. 

 Coleus elongatus must have evolved on the summit of Ritigala, where it exists as about 

 a dozen individuals, and cannot ever have been much more numerous. The most 

 numerous group of the Ceylon endemics are these " very rares " — " very rares " 

 meaning the minimum area ; and the numbers decrease steadily up to the " very 

 common " — " very common " meaning the maximum area (for the endemics under 

 consideration). 



But there is no need, says Dr. Willis, to confine the hypothesis to one country. 

 Holding good, as it does, for all, it must be general, and we may say that widely spread 

 species are in general the oldest and first evolved, very local species the youngest and 

 last evolved. 



Take a slightly earlier paper by Dr. Willis, " Endemic Genera of Plants in their 

 Relation to Others," Ann. Bot., XXXV (October, 1921), p. 503, in which he says : — 



" So firmly has the old view, that endemics are relics of old floras held sway, that it never seems to 

 have occurred to any botanist to try the simple test whose results I am about to set forth, and yet this 

 test may have been made at any time in the last thirty years." 



He has published his views at length in an admirable work, " Age and Area " 

 (Cambridge University Press, 1922), to which I refer my readers for a lull statement 

 of his arguments. 



At the same time, it is proper to state that his remarks do not command universal 

 acceptance amongst students, a prominent criticism being that of Bateson's review of 

 the work in Nature, of 13th January, 1923, pp. 39-43. See also the discussion before 

 the Linnean Society, reported in Nature, of 2nd December, 1922. In the course of that 

 discussion, Prof. A. C. Seward pointed out that as regards Conifers and Ferns, study 

 showed that the forms existing now in restricted areas were the oldest and not the 

 youngest. Willis refutes this in quoting distribution of Australian Callitris. 



In " Natural Selection and the Dispersal of Species " by Edwin Bingham 

 Copeland, Philippine Journal of Science," C, Botany, XI, 147 (July, 1916), the author 

 presents himself "as a confirmed adherent of the doctrine of natural selection," and 

 adopts a different position to that of Dr. Willis. 



Dr. Willis candidly meets some of his objectors in a chapter of his work specially 

 devoted to Objections to the Hypothesis. See also his paper in Ann. Bot. for April, 1923, 

 p. 193. 



Now we come to " Age and Area : a Review of J. C. Willis' Theory of the Origin 



of Species," by Hugo de Vries, Journal of Heredity, XIV, 171 (July, 1923). 



" J. C. Willis has tried to show that the dispersal of plants is governed by general laws and independent 

 of so-called adaptations, or of any kind of advantageous response to local conditions. The main factor of 

 distribution is age, a cause which works in the same manner on all plants . . . The same analogy 

 that connects Jordanian with Linnean species is thus connecting species and genera also. The new law, 

 that age goes parallel to area, and that the method of evolution and distribution have been, in the main, 

 the same in all branches of the animal and vegetable kingdom, seems to be the principle which must direct 

 llfurther researches in the geography as well as the genealogy of the lmng world." 



