A DOMINANT MENDELIAN CHARACTER. 307 
These differences of shape were found in the wild species as well as in the 
cultivated, but I have come across examples, such as specimens ki (F1, 
Congo x Flourball), K9?, 40 (F? of same cross), and several others, which 
have pollen quite as perfect and more abundant than any wild type. 
On the other hand, the majority of the commercial potatoes have but little 
pollen, and what there is consists largely of irregular grains which, 16 must 
be remembered, are sterile aborted grains. Notable exceptions are Flourball, 
Early Regent, and Reading Russet. 
In Table I. is given a list of the wild forms, and in Table IL. a few of the 
domestie potatoes, and examples of those that have arisen in the course of my 
experimental work on the domestic varieties. 
It will be seen from the tables that there is no essential difference whatever 
between the wild species and the domestic varieties. Thus S. Commersonii, 
which is one of the most distinct forms, is not so pure to the oval type as 
many domestic sorts, such as Flourball or Reading Russet. ©. tuberosum is 
the most completely oval, but, even so, it is with difficulty to be differentiated, 
in respect of purity and shape, from K* ORT, Congo x Flourball). The grains 
of the latter are, however, larger and far more abundant than those of 
S. tuberosum. 
The irregular grains of 5, Соттетзопа and the other species are not to be 
distinguished from the irregular grains of any domestic variety which has 
plenty of pollen ; they should not, however, be compared with the irregular 
grains of those varieties which, having but few grains in the anther, are 
practically sterile, for these few grains are often imperfect mother-cells, and 
frequently are twin-cells. 
Mr. Sutton * has described the variety which was identified as Solanum 
etuberosum + by Mr. Lindsay of the Edin. Bot. Gardens, and has kindly visited 
my garden in order to make sure of the identity of the potato obtained from 
Kew, and grown by myself, with that which he has grown at Reading during 
the last twenty years. The two potatoes are in his and my opinion without 
doubt the same. Аз my observations on the pollen of this variety and its 
seedlings vary a little from those of Mr. Sutton’s, it has seemed best to add 
here a short description of my findings, though I hope to publish later a fuller 
note on this variety 1. 
S. etuberosum set seed in my garden in 1908, and in 1909 some 50 seed- 
lings were grown showing a degree of variation that was as extraordinary 
as Ц was unexpected. 
The pollen of the parent plant was examined at various intervals during 
the summer of 1909, and, as is shown in the table, deteriorated as the season 
* Journ. Linn. Soc., Bot. vol. xxxviii. 1909, p. 448, tab. 406, 
+ Although styled “ etuberosum ” there is no doubt that it is not the potato so described 
by Lindley. 
{ Journ. Genetics, 1910, vol. 1. 
