508 



THE AMERICAN NATURALIST 



[Vol. XLIV 



Mespilus graft hybrid, and H. Winkler's tomato-nightshade 

 graft hybrid. The suggestion that the vegetative point of such 

 forms consists of a more or less irregular mixture of the two 

 tissues could hardly be true because one or the other tissue would 

 soon gain the ascendency. Baur suggests that a careful study 

 of mitosis in the vegetative point of such forms might settle the 



East has recently published an interesting paper 3 dealing 

 With the effect of selection on fluctuations. The conclusion is 

 reached that neither the relative content of dry matter nor that 

 of the nitrogenous matters of the potato can be changed by the 

 selection of fluctuations and their subsequent asexual reproduc- 

 tion. In most potato fields there will occasionally be found 

 plants which remain green after the main crop has matured and 

 the vines died. East made a selection of plants maturing early 

 and those maturing late, in some cases finding lateness or easi- 

 ness reproduced in the selection, in others not. In one of these 

 cases the long-lived plants selected from a variety were found to 

 have pink sprouts, while a short-lived plant from the same 

 variety had white sprouts. East suggests tlt.it cither bud varia- 

 tion had taken place or that there had been an accidental mixing 



There has been a good deal of work on selection for yield and 

 other characteristics in old agricultural varieties, which indicate 

 that bud variations or permanent mutations of one kind or an- 

 other occasionally take place in such varieties, and that they 

 gradually break up into a mixture of biotypes, which may differ 

 in a considerable number of characteristics, including yielding 

 power. Selection within such a variety might then result in 

 the isolation of strains of better quality than the general average 

 of the variety. 



It seems to the writer that Dr. East has hardly given sufficient 

 attention to the possibility of selection for improvement in old 

 strains in which a considerable number of important mutations 

 may have occurred. For instance, he says : 



As a result of these experiments I will not go so far as to say that 



bility that the commercial grower will obtain disease-resisting varieties 

 So far as newly isolated pure strains are concerned, the writer 



Reproduction," Connecticut Experiment stnti-.n hv,„,rr. 1«hi9-10, pp. 119- 



