Mutations 221 



governed by Natural Selection, just as much as the specialisation of 

 the rostellum in an Orchid, or of the pappus in a Composite. 



Did space allow, other examples might be added. We may 

 venture to maintain that the glimpses Avhich the fossil record allows 

 us into early stages in the evolution of organs now of high systematic 

 importance, by no means justify the belief in any essential distinction 

 between morphological and adaptive characters. 



Another point, closely connected with Darwin's theory, on which 

 the fossil history of plants has been supposed to have some bearing, 

 is the question of Mutation, as opposed to indefinite variation. 

 Arber and Parkin, in their interesting memoir on the Origin of 

 Angiosperais, have suggested calling in Mutation to explain the ap- 

 parently sudden transition from the cycadean to the angiospermous 

 type of foliage, in late Mesozoic times, though they express themselves 

 w ith much caution, and point out " a distinct danger that Mutation 

 may become the last resort of the phylogenetically destitute " ! 



The distinguished French palaeobotanists,Grand'Eury ^and Zeiller-, 

 are of opinion, to quote the words of the latter writer, that the facts 

 of fossil Botany are in agreement with the sudden appearance of 

 new forms, differing by marked characters from those that have given 

 them birth ; he adds that these results give more amplitude to this 

 idea of Mutation, extending it to gi'oups of a higher order, and even 

 revealing the existence of discontinuous series between the suc- 

 cessive terms of which we yet recognise bonds of filiation ^ 



If Zeiller's opinion should be confirmed, it would no doubt be a 

 serious blow to the Darwinian theory. As Darwin said : " Under a 

 scientific point of view, and as leading to further investigation, but 

 little advantage is gained by believing that new forms are suddenly 

 developed in an inexplicable manner from old and widely different 

 fonns, over the old belief in the creation of species from the dust of 

 the earth*." 



It must however be pointed out, that such mutations as Zeiller, 

 and to some extent Arber and Parkin, appear to have in view, bridging 

 the gulf between different Orders and Classes, bear no relation to 

 any mutations which have been actually observed, such as the com- 

 paratively small changes, of sub-specific value, described by De Yries 

 in the type-case of Oenothera Lamarckiana. The results of palaeo- 

 botanical research have undoubtedly tended to fill up gaps in the 

 Natural System of plants — that many such gaps still persist is not 



* C. Grand'Eury, "Sur lea mutations de quelqaes Plantes fossiles du Teiraiu houiller." 

 Comptes Rendus, cxi.ii. p. 25, lOOG. 



* R. Zeiller, " Lcs Veyolaux fossiles et leurs Enchalnements," Revue du Mois, ni. 

 February, 1907. 



^ loc. cit. p. 23. * Origin of Species, p. 424. 



