No. 602] THE SELECTION PROBLEM 



doubt or question the reason for the success is because by 

 this method tve select directly the kind of gametes we 

 want. In ordinary Darwinian selection we select the 

 hind of somata we want, and trust blindly that a wise 

 providence has implanted in them the sort of gametes we 

 need in order to get further somata like those we selected. 

 And as in so many other troublesome affairs in this vale 

 of tears, too often we find in the outcome that our trust 

 has been misplaced! 



It seems to me that whether Morgan's suggestion re- 

 garding the highly interesting and important results with 

 Difflugia is true or not the fact dealt with in the pre- 

 ceding paragraph objectively parallels exactly the phe- 

 nomena which one sees when he isolates pure lines 

 from a mixed population (e. g., in oats). He finds some 

 individuals which are somatically what he wants but 

 which fail to produce the sort of progeny he is looking 

 for. These he discards. Others produce progeny which 

 are like themselves. They transmit^^ their qualities and 

 hence are retained. 



Having considered the results of experiments on selec- 

 tion in pure lines we may turn to similar experiments 

 with sexually reproducing organisms. Here the facts 

 are, in the main, no less clear, but they are, on the whole, 

 exactly opposite in their sense, at first sight at least. For 

 in most of the experiments of this sort selection has been 

 attended with an alteration of the type in the direction of 

 the selection. This has been the case in the writer 's^^^ 

 experiments on egg production, in the domestic fowl since 

 1908, in the work of Smith^^ and others with maize in 



5* Lest there should be any misunderstaBding I may say that I am fully 

 aware that the old idea of heredity as a direct and material transmission of 

 personal qualities from generation to generation is tvholly incorrect, out-of 

 date, and pedagogically pernicious. I find it, however, extremely conve- 

 nient, saving of breath and good white paper, and, with this explanation, 

 I hope permissible, to use "transmit" as a technical genetic term meaning 

 "to possess gametes of such sort as will produce in the progeny." 



65 Pearl, E., Amer. Nat., Vol. XLTV, pp. 595-608, 1915. 



68 Smith, L. H., III. Agr. Expt. Stat. Bui. 128, 1908. 



