12 



BULLETIN 195, U. S. DEPAETMENT OF AGEICTJLTUEE. 



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 iia this case the failure to set fruit was probably a clear 

 example of nonafBuity. The next female parent, Sophie, crossed 

 with Keeper, gave excellent results. Sophie is a German variety 

 possessing quahties 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 insuflacient 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. 



Geheimrat Theil X Keeper.-. , 



Geheimrat Theil X XX Early 



Geheimrat Theil X Solanum maglia 



Geheimrat Theil X Solanum sp i 



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 eiuberosum Lind . 



Puerst Bismarck X Apollo 



Fuerst Bismarck X Harris Snowball 



Fuerst B ismarck X June 



Apollo X E arly Silverskin 



Apollo X Empire State. 



Apollo X Irish Seedling 



Daisy X Keeper 



Daisy X Early Silverskin 



Daisy X Round Pinkeye 



Num- 

 ber of 

 flowers 

 crossed , 



Num- 

 ber of 

 seed 

 balls de- 

 veloped. 



Percent- 

 age of 

 success. 



S3. 3 



9.1 









 80 













 100 





 75 

 100 

 92.3 





 50 









 81.8 









 41.7 









 26 





 42.9 

 SO 

 41.7 

 50 



Number 

 of tuber- 

 bearing 

 seedlings 



502 















2,244 















707 







275 



555 



326 







159 











640 











1S8 











50 







243 



453 



329 



180 



Average 

 number 

 of seed- 

 lings per 

 seed ball. 



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. 



