18 BULLETIN 1&5, U. S. DEPARTMENT OF AGEICULTUEE. 



The G seed balls from cross 8708, Irish Cobbler X Irish Seedhng, in 

 which but 6 flowers were pollinated, produced a total of 964 seeds, or 

 an average of 160.7 seeds per berry. The number of seeds in each 

 berry varied from 57 in seed ball d to 256 in seed ball e. A f au' degree 

 of uniformity in the percentage of germination is to be noted. 



The cross 8709, Irish Cobbler X Irish Seedling, resulted in 5 seed 

 balls from 7 flowers pollinated, and these developed 984 seeds, or an 

 average of 196.8 seeds per berry. The number of seeds from the 

 individual seed balls ranged from 134 to 289 and the percentage of 

 germination from 71.6 to 91.3. 



In the thu-d cross, 8718, Eureka X Keeper, 5 seed balls resulted 

 from 7 flowers poHinated, and these produced 1,154 seeds, or an aver- 

 age of 230.8 seeds per berry, the percentage of germination varying 

 from 73.1 to 84.1. 



The highest number of seeds from an individual seed ball was from 

 8718-Z>, which produced 297 seeds. Another point of interest in 

 these crosses which has not as yet been emphasized is that the seed 

 balls were produced in each case on the same cyme or flower cluster. 

 It is generally believed by potato breeders that the raising of more 

 than one or two seed balls in a cluster is undesirable. On this point 

 East ^ says: 



It is also desirable to stimulate tlie growtli activity in tBe flower stalk by pollinating 

 four or five flowers on one cyme; then after the berries are partially developed, pinch 

 off the poorest and allow only two to develop to maturity. 



In a more recent pubHcation ^ East states that the proj)riety of this 

 procedure is doubtful. 



In view of the data which have just been presented it does not 

 appear that the development of seed was curtailed in the shghtest, 

 with the possible exception of 8708-(^, or that the germination was 

 impaired, at least not so far as any data are available to refute it. It 

 is true that the germination as a whole is not high for solanaceous 

 seeds; yet if we take into consideration the fact that every seed 

 removed from the seed ball was counted and that the number of 

 seedlings given is the actual number that reached the potting stage,, 

 the showing made should be considered very satisfactorj^. 



METHOD OF GROWING AND TESTING SEEDLINGS. 



In order to insure a good development during the first season it ia 

 rather essential that the seedling should be allowed a long growing 

 period. To do this it is necessary to start the seeds in a greenhouse 

 or in a hotbed. In the latitude of Washington, in order to insure 

 stocky plants in 3-inch pots, ready to be transferred to the field early 



1 East, E. M. Tedmique of hybridizing the potato. In Proc. See. Hort. Sci., 1907, p. 35-40, 1908. 

 (Seep. 39.) 



2 East, E. M. Some essential points in potato breeding. Conn. Agr. Exp. Sta., 31st and 32d Hpt^ 

 (1907-08), p. 429-447, pi. 41, 1908. (See p. 441.) 



