IV.] EVOLUTION IN BEANS. 129 



cultivation.* Even in its wild state it is scarcely more 

 distinct from the common races of maize than the "husk 

 corn" is, or the curious striped -leaved corn of Japan — 

 and the latter would certainly be considered worthy of 

 specific recognition by botanists were it not for the fact 

 that historical evidence shows that maize was introduced 

 into Japan directly or indirectly from the New World, 

 and that, therefore, its origin is more or less enshrouded 

 in knowledge ! All this is but another illustration of 

 how tenaciously botanists still hold to the Linnaean idea 

 of species whilst they profess the Darwinian idea. 



A similar evolution of types which are as distinct and 

 permanent as accepted species in the same genus are, is 

 Avell illustrated in the various beans. The common gar- 

 den or kidney bean was made into two species by Lin- 

 naeus, the pole beans {Phaseolus vuhjaris) and the bush 

 beans (P. nanus). Since it has been demonstrated by 

 experience and experiment that these groups are inter- 

 changeable forms of one type, botanists have discarded 

 Linnaeus 's designations of them, and now call the gar- 

 den bean a single species; yet it should be said that a 

 more explicit and satisfactory instance of the evolution 

 of specific forms right under our own observation could 

 not be demanded. The two groups are species until we 

 discover that they have sprung from one type within 

 historic times, whereupon we then regard them not as 

 species but as anomalies of cultivation. Von Martens, 

 however, discards origin as a mark of specific likeness or 

 difference, and now proposes to erect seven species upon 

 the obvious racial differences in the garden beans. But 

 the most interesting feature of this bean botany is the 



*For an account of this corn under cultivation, see Bulletin 49 CorneH 

 Experiment Station. 

 9 SUR. 



