254 University of California Publications in Botany [Vol.5 



whether or not the castration had been complete. This examination 

 showed that, of over 800 castrations, in only one case had anthers 

 been overlooked. Two anthers were present on the withered corollas 

 from the castration of two buds on plant 25 and, as will be seen, 

 a fair proportion of good seed resulted (cf. table 1). The corollas 

 are, in most cases, still available for examination in the seed packets 

 together with the seed not sown. 



The third essential point had to do with the technique and 

 manipulation concerned in treating the buds. For any one familiar 

 with the technique of making hybrids through cross-pollination the 

 essential precautions to prevent contamination by foreign pollen be- 

 come second nature. The important point, in addition to this most 

 essential one, in such operations is the delicacy with which the manip- 

 ulations can be performed to prevent injury to the flower parts not 

 to be treated. The profusion of flowering laterals on the plants used 

 in the experiments herein described made it necessary to cut away 

 masses of flowers, from other inflorescences, near the bud before it 

 could be operated upon. In a certain number of cases this was 

 not carefully enough done and the close proximity of flowers about 

 the bud after its castration made it seem best to discard it. A 

 number of such doubtful castrations were, however, bagged and in 

 one case undoubtedly self-pollinated seed in fair proportion was pro- 

 duced — i.e., plant 14 (table 1). The buds were, with the exception 

 of the smallest, slightly split open along the upper third of the corolla 

 tube and the castrations or mutilations performed through this slight 

 opening, which was not sufficient in extent to expose the stigma. 

 If. in picking out the anthers, the stigma was inadvertently touched 

 by the forceps the bud was discarded. 



The treatment given the 800 buds employed was of three types only. 

 The first consisted of simple emasculation of the flower by picking 

 off the anthers of the bud near the tops of the filaments. The second 

 involved the removal of the stigma as well as the anthers. The 

 stigma in such cases was pinched off with the forceps, before pick- 

 ing out the anthers, at the very top of the style. In the third type 

 of treatment the stigma was pinched off, in the above manner, but 

 the anthers were allowed to remain untouched. In such cases the 

 tip of the style, somewhat crushed, had dried down exceedingly before 

 any pollen could have been shed in the open flower. The last two 

 types of treatment will hereafter be referred to as "mutilations." 



