POTATO BEEEDING AND SELECTION. 21 



The results secured from our own studies as presented in Table IV 

 are not entirely in accord with Salaman's deductions. For example, 

 in a population of 1,425 seedlings from a cross between Irish Cobbler 

 and Irish Seedling, the first parent having a creamy white skin and 

 purplish tinged sprouts and the latter with flesh-tinted skin and 

 purplish sprouts, color was absent in 70.2 per cent of the tubers. 

 Of those showing color, 36 were mottled with white, 229 were flesh, 

 104 were red, 55 were purple, and 1 was violet-black. In another 

 instance, out of a population of 870 seedlings of Irish Cobbler crossed 

 with Keeper, color was absent in 69.7 per cent of the tubers. The 

 pollen parent. Keeper, being a red-skinned variety, it would seem 

 that if white were recessive a larger proportion of the F^ generation 

 should have shown color. Almost identical figures were secured 

 when Extra Early Eureka and Keeper were crossed. In this case, 

 in a population of 680, color was absent in 70.6 per cent, or a difference 

 of but nine-tenths of 1 per cent between the two crosses. In view of 

 the fact that the writer regards Irish Cobbler and Extra Early 

 Eureka as one and the same variety, the parentage of the two crosses 

 is thus identical. When it is considered that the data for the two 

 crosses were secured and tabulated independently of each other, 

 the uniformity of the data is all the more remarkable. When the 

 Irish Cobbler is crossed with a Chilean seedling, a different set of 

 data is obtained. In a population of 214, only 34.1 per cent of the 

 tubers were free from color. 



When white-skinned and white-sprouted varieties were crossed 

 with red-skinned varieties, the proportion of white-skinned seed- 

 lings was larger, as is shown in the following crosses: Green Mountain 

 X Keeper produced 88 seedlings, of which 79.5 percent were devoid 

 of color; of those which did show color, 11 were mottled, 6 flesh, 1 

 nisset, and 1 red. Gold Coin X Keeper produced 322 seedlings, of 

 which 79.8 per cent were devoid of color; and of those which showed 

 color 28 were mottled, 32 were flesh, and 5 were red. The remark- 

 able similarity of color expression of these two crosses is again 

 accounted for by the fact that the varieties Green Moimtain and 

 Gold Coin are regarded as identical or so nearly so as to be practically 

 indistinguishable from each other. 



While numerous other examples might be cited, it is believed that 

 suflicient <1ata have been presented to justify the assertion that 

 white is not a recessiv<! character in the seedlings of the crosses just 

 jiiuru'd. 



POTATO IMPROVEMENT RY SELECTION. 



Th(^ inif)r(jvenient of tli(; potato by selection alone restricls the 

 operator to sucii variations as may occur within the variety. Fortu- 

 nately, this field of endeavor is not such a limited one as it might at 

 first appear to ii luynniti, since considerable vnriuliou idieady (exists 



