148 TEST CASES [ch. xiii 



however, seem to belong to the vegetation that was largely 

 destroyed there by the ice. But things like Artocarpus, with 

 over sixty species, common in warm Asia, are now being called 

 relics, because they have fossils in places not now occupied by 

 them. But if these plants are to be counted relics, one might as 

 well say that all widely distributed things, but probably not the 

 local or endemic, are relics, for there are few widely distributed 

 things that have not the possibility of fossils somewhere, for 

 example the whole British flora that anywhere reaches the coast. 

 There are rarely any fossils of the small and local genera that are 

 usually called relics. 



But the hypothesis of relicdom is no better than that of local 

 adaptation in explaining the intermediate position of the 

 Ceylon-South Indian things in the distribution. Are they half 

 relics? No hypothesis other than that which we have termed age 

 and area can explain the "hollow curve" into which all kinds of 

 distribution fit. No theory involving natural selection or gradual 

 adaptation can explain why 38 per cent of the genera of the 

 world have only one species, 13 per cent two, and only 7 per cent 

 three, and why the proportions are very much the same wherever 

 one may go. There is no escape from these facts, and to say that 

 they are accidental is simply to admit that the distribution of 

 plants is largely accidental, and to ignore the rule under which 

 they have probably come into being, the simple doubling of 

 every species at intervals as time has gone on (cf. Yule, 75). The 

 author has lately shown that the distribution of family sur- 

 names in the mountainous regions of Switzerland follows exactly 

 the same rules as does the distribution of plants. No invocation 

 of natural selection can explain why Rochat, which is a common 

 name in its place of origin (the valley of Joux), should have spread 

 more widely in the canton of Vaud than Capt, which is less 

 common, or why the surnames should be arranged in "wheels 

 within wheels" just like the species of the Ceylon or other floras. 

 Nor can one invoke gradual adaptation to explain why in the far 

 north-east of its range, Rochat is replaced by Rojard, which is 

 much more easily explained by the general illiteracy of former 

 days, and largely matches the way in which plant varieties occur. 

 It wfll perhaps be well to quote part of the original note, by kind 

 permission of the Linnean Society (and cf. fig. 6, p. 40). 



