102 PROBLEMS OF GENETICS 



of factors, such as is to be seen in so many generations of plants 

 derived from a cross involving many genetic elements. The 

 'first question is what is Oenothera Lamarckiana? Is it itself a 

 plant of hybrid origin? To this fundamental question no satis- 

 factory answer has yet been given. All attempts to find it as a 

 wild plant in America have failed. It existed in Europe in the 

 latter half of the eighteenth century. Whence it came is still 

 uncertain, but the view that it came into existence in Europe and 

 perhaps in Paris, seems on the whole the most probable. The 

 question has been debated by Macdougal, Gates, and Davis. 

 From historical sources there is little expectation of further 

 light. Those who favour the notion of a hybrid origin look on 

 Oenothera biennis as one of the putative parents. It has been 

 conjectured that a species called grandiflora lately re-discovered 

 on the Alabama river was the other parent. Experiments have 

 been instituted by Davis to discover whether Lamarckiana can 

 be made artificially by crossing these two species. The results 

 so far have shown that while plants approximating in various 

 respects to Lamarckiana have thus been produced, none agree 

 exactly with that form. Davis, to whom reference should be 

 made for a full account of the present state of the enquiry, 

 points out that there are many strains of biennis in existence 

 and that it is by no means impossible that by using others of 

 these strains a still closer approximation can be made. None 

 of Davis's artificial productions as yet breed at all true, as 

 Lamarckiana on the whole does. In such a case, however, where 

 several characters are involved, this is perhaps hardly to be 

 expected. 



One feature of the Oenotheras is very curious. Not only 

 Lamarckiana, but all the allied species so far as I am aware, 

 have a considerable proportion of bad and shrivelled pollen 

 grains. This is undoubtedly true of species living in the wild 

 state as well as of those in cultivation. I have had opportunities 

 of verifying this for myself in the United States. No one looking 

 at the pollen of an Oenothera would doubt that it was taken from 

 some hybrid plant exhibiting partial sterility. On the other 

 hand, it is difficult to suppose that numbers, perhaps all, of the 



