CH. XII] C. TAXONOMIC 141 



of Nepenthes^ for example, so that the adaptation which enabled 

 the genus to spread must have been generic, perhaps principally 

 the pitcher. But if so, why could not some species have been able 

 to live in America, or some Sarracenias in Europe? No feature 

 can be pointed out in the pitcher or any other character of 

 Nepenthes, which should limit it to its present distribution. 

 Sarracenia, as pointed out on p. 56, is naturalised in a bog near 

 Montreux. Nothing but an explanation based upon age and 

 area will answer the innumerable questions like this w^hich come 

 up in a study of distribution. 



This feature, that the enormous distribution of large genera 

 like Carex or Senecio can only be explained by generic adapta- 

 tion, if one is to accept the "explanation" given by natural 

 selection, is a very fatal objection to the theory. The six genera 

 above mentioned average a thousand species each, and it is a 

 very astonishing thing that the original adaptations should have 

 been such that they remain in their progeny after all this degree 

 of change. 



As in general we are not alwavs verv sure of what we mean 

 when we say that one genus is more complex than another, and 

 as opposite views are frequently expressed in any particular 

 case, it is fortunate that in the Podostemaceae and Tristicha- 

 ceae we have families where it is almost impossible to be in 

 doubt, for the obvious change that has gone on is from a slight 

 to a great dorsiventrality. The comparatively primitive forms 

 are widely dispersed, the more modified are local. 



It is fortunate that we have this evidence, for usually it is not 

 easy to draw conclusions from the morphology. It is often said, 

 for example, that reduction in number of stamens and carpels is 

 evidence of progress, yet we can find the widely dispersed species 

 in some families showing the one thing, the narrowly dispersed 

 in others. For example, with leaves alternate/opposite, the 

 Erythroxylaceae go one way, the Caryocaraceae the other; with 

 flow^ers regular/irregular, Aristolochiaceae and Commelinaceae 

 go one way, Dichapetalaceae the other. With corolla valvate/con- 

 volute, Quiinaceae go one way, Cistaceae the other, with stamens 

 cX)/few we have Loasaceae and Papaveraceae/Quiinaceae and 

 Velloziaceae. With carpels oo/few, Papaveraceae/Portulacaceae, 

 and so on indefinitelv. 



