STERILITIES OF WILD AND CULTIVATED POTATOES. 
17 
Table 2. — Typical results for varieties of potatoes classed as A and B with respect to 
ability to produce fmit, crossed with varieties placed in classes 1, 2, and S, respectively, 
with regard to the quality of their pollen — Continued. 
Grade of pollen of male parent. 
,s3. 
Class 1 . 
Class 2. 
Clas 
Number 
of 
flowers 
crossed. 
Number 
of seed 
balls. 
Number 
of 
flowers 
crossed. 
Number 
of seed 
baUs. 
Number j Numb(>r 
flowers 1 baU? 
crossed, j DdU:j - 
CLASS B VARIETIES. 
16 

12 1 
10 
12 1 
45 I 3 
19 j 
6 
British QueenX Seedling 24642 
British QueenX Seedling 40568. .. 
12 
64 
16 
17 

4 
7 

Charles DowningX Seedling 24642 
Charles DowningX Seedling 40108 
fViTriTnings' PridfiVClio . . 
r.nTnmings' PridflVSflftdling 2464)2 . ..... 6 
Triumph xSeedling 24642 61 1 8 
Triumph X Seedling 40108 1 9| 2 
TriumphXEarlv Standard (Dreer's) 
21 

7 
25 

Triumph X Irish Cobbler : 

The classification of the various varieties and seedlings studied, 
both in regard to the condition of anthers and of pollen (classes 1, 2, 3, 
and 4) and with respect to ability to produce fruit (classes A, B, 
C, and D) is given in Table 3. 
Under the conditions at Presque Isle, where flowers are produced 
in abundance, most varieties, if not all of them, are able to function 
as seed parents when properly pollinated with viable pollen. This 
is well shown by the very unusual development of fruit in those 
varieties and seedlings having considerable viable pollen. Of the 
588 seedlings of the 1921 sowing kept in 1922 and planted in five- 
hill units, 81 produced seed balls to open pollination. Of the 188 
seedlings of previous years grown in 1922, 56 were producing seed 
balls, and for one of these, No. 39477, the fruits were especially 
abundant (PL VIII, fig. 1). The pollen of many of these which 
produced fruit was tested, and in every case it was found to be in 
class 1 (PL V, fig. 2) . A few varieties seem low in ability to produce 
fruit (class B), but according to present data none are to be placed 
in class C as entirely unable to produce fruit. 
Evidence of a parthenocarpic development of fruits has been found 
in 14 varieties, including Rose Xo. 4 and most members of the Bur- 
bank and Rural groups. At the time of the opening of the flowers, 
the ovaries of many pistils are decidedly enlarged and the anthers 
and corollas before they wither are pushed forward and to one side 
by the rapidly enlarging ovaries (PL VII, fig. 1). Such fruits sel- 
dom, if ever, contain seeds (PL VII, fig. 2). They may reach a good 
size, but usually fall before they are fully ripe. Several of the varieties 
exhibiting this tendency are known to be good seed producers when 
