18 Colour and other Characters in the Potato 



On Plate V, Nos. 67, S7, 91, 94, only further illustrate the fact that 

 though certain tubers of a plant in this family may be more or less 

 oval, yet other tubers on the same plant will be found to be of this 

 peculiar " round " type. 



One exception, however, stands out, and this is No. 100, which is 

 definitely unlike the parent type and all its 100 other sister plants. 



It is possible that it arose from a stray tuber and does not belong 

 to this series at all — a view that has some plausibility, seeing that two 

 years before " Flourball" seedlings vvere grown on this ground. Efforts 

 are being made this year (1910) to obtain selfed seed from this plant. 



On Plate VI a further illustration {G family) of this " round " type 

 of potato is seen; it arose from a "Flourball" plant, but not the same 

 one as the line A. 



Seed from four of these plants has been saved and a batch of seed- 

 lings of G* were planted in October 1909 and hurried forward; on 

 April 26, 1910, they were examined and all the seedlings bore tubers, 

 varying from ^ to f in. diameter, true " rounds " in shape. Those 

 of the G^ seedlings which have formed tubers have also developed 

 typically " round " ones'. 



It thus appears that there is a certain definite type of " round " 

 potato that can be extracted from Sutton's " Flourball," and which can 

 be bred sexually pure through at least two generations after having 

 been isolated. 



Before following further the evidence as regards the heredity of this 

 type and its behaviour when crossed with other types, it will be best to 

 discuss more fully its shape and variations. 



The tuber shape, which is under consideration and which for the 

 purposes of my work I have called " round," is to be found white, or 

 coloured as red or black. 



No relation has in the course of this research been shown to exist 

 between shape of any kind and the pigmentation either of haulm or 

 tubers. 



The "round" tubers may be furnished either with "deep" or "fleet" 

 eyes. It will be shown later that depth of the eye is itself a character 

 inherited on Mendelian lines, and my experiments fail to show any 

 relationship between depth of eye and shape of tuber. The size of the 

 tuber is of course variable, but I have not found, however one may have 



^ Aug. 29, 1910. Although the G family has not been completely harvested there is 

 evidence that the G-' family consists of three " longs " to one " round," and that the G' 

 and G* families are pure to " roundness." 



