12 
BULLETIN 195, U. S. DEPARTMENT OF AGRICULTURE. 
results were obtained when pollen of the unnamed Mexican species 
of Solanum was used. We know that S. maglia produces pollen very 
sparingly and that frequent attempts to germinate the pollen in 
the laboratory have been unsuccessful. The Mexican species 
is known to produce viable pollen in abundance, however, so 
that in this case the failure to set fruit was probably a clear 
example of nonafnnity. The next female parent, Sophie, crossed 
with Keeper, gave excellent results. Sophie is a German variety 
possessing qualities of vine and tuber strongly resistant to 
late-blight. From 20 pollinated flowers 16 seed balls were devel- 
oped. The seeds from the 16 seed balls produced 2,244 tuber-bearing 
plants, or an average. of 140.3 plants per berry. The 4 pollinated 
flowers of Sophie X Fuerst Bismarck failed to develop a single berry. 
A similar result was obtained from 8 flowers pollinated with Empire 
State and from 4 pollinated with Garnet Chili. Sophie X Irish Seed- 
ling produced 4 seed balls from the 4 flowers pollinated. The seeds 
from these berries gave 707 tuber-bearing plants, or an average of 
176.8 plants per berry. Three flowers pollinated with Venezuela 
failed to set fruit. It is clearly evident that the varieties Fuerst 
Bismarck, Empire State, Garnet Chili, and Venezuela either did not 
develop viable pollen or the pollen tubes were unable to reach the 
ovules of the flower. It is known that all of these varieties produce 
pollen sparingly, and it is probable that an insufficient quantity of 
viable pollen was present to effect the cross. 
Table I. — Record of potato crosses made at Burlington, Vt., in 1909. 
Parentage of cross. 
Num- 
ber of 
flowers 
crossed . 
Num- 
ber of 
seed 
balls de- 
veloped. 
Percent- 
age of 
success. 
Number 
of tuber- 
bearing 
seedlings. 
6 
5 
83.3 
502 
11 
1 
9.1 

3 



2 



20 
16 
80 
2,244 
4 
6 


8 



4 



4 
4 
100 
707 
3 



12 
9 
75 
275 
15 
15 
100 
555 
13 
12 
92.3 
326 
4 



8 
4 
50 
159 
13 



8 



11 
9 
81.8 
640 
8 



21 



12 
5 
41.7 
188 




3 



16 
4 
25 
50 
8 



7 
3 
42.9 
243 
5 
4 
80 
453 
12 
5 
41.7 
329 
8 
4 
50 
180 
Average 
number 
of seed- 
lings per 
seed ball. 
Geheimrat Theil X Keeper 
Gekeimrat Theil X XX Early 
Geheimrat Theil X Solanum maglia 
Geheimrat Theil X Solanum sp 1 
Sophie X Keeper 
Sophie X Fuerst Bismarck 
Sophie X Empire State 
Sophie X Garnet Chili 
Sophie X Irish Seedling 
Sophie X Venezuela 
Professor Maerker 506 X Apollo 
Professor Maerker X Early Silverskin 
Professor Maerker X Keeper 
Professor Maerker X Rand's Peachblow 
President Kruger X Apollo 
President Kruger X Gem of Aroostook 
President Kruger X Green Mountain 
President Kruger X Keeper 
President Kruger X Star of the East 
President Kruger X Solanum etuberosum Lind 
Fuerst Bismarck X Apollo 
Fuerst Bismarck X Harris Snowball 
Fuerst Bismarck X June 
Apollo X Early Silverskin 
Apollo X Empire State 
Apollo X Irish Seedling 
Daisy X Keeper 
Daisy X Early Silverskin 
Daisy X Round Pinkeye 
100.4 



140.3 



176.8 

30.6 
37 
27.2 

39.8 


71.1 


37.6 


12.5 

81 
113.3 
65.8 
45 
i Mexican species. 
