264 University of California Puhlications in Botany [Vol.5 



Hartley (1902, p. 15) makes the following statement concerning 

 certain of his interesting experiments on floAvers of "Cuban Tobacco 

 (Nicotiana tahaccum)" : "Of 60 emasculated flowers that had their 

 stigmas covered with substances other than pollen, 1-1 set fruits, 

 while of 20 that were emasculated but never pollinated, 2 set fruits. ' ' 

 Continuing, he says: 



As a general thing the capsules, resulting from flowers that were not pol- 

 linated, and likewise those resulting from flowers whose stigmas were covered 

 with some substance other than pollen, contained only small, compressed, 

 undeveloped seeds, but the two pods obtained ... by treating the fully 

 receptive stigmas with magnesium sulphate contained some spherical seeds of 

 almost full size which looked like good seeds, but when cut into proved to be 

 hollow spheres. 



]Mrs. Thomas' results have been detailed elsewhere in this paper. 

 Summarizing these previous efforts to obtain parthenogenetic seed 

 in Nicotiana, we may state that of the many thousands of castrations 

 and mutilations of flowers concerned in all the experiments above 

 noted, only two capsules containing viable seeds were produced. This 

 statement leaves out of account Mrs. Thomas' remarkable results. 

 In only a few cases also, and then only after artificial stimulation, 

 did these castrated flowers produce normal fruits. In the majority 

 of cases where normal fruits were thus produced, abortive seed was 

 formed in the mature capsules. Accompanying the general failure 

 of castrated and mutilated flowers to mature fruits, the early falling 

 of the flowers has attracted attention. It is therefore remarkable 

 that in the experiments, some of which are shown in table 1, there 

 should be a striking absence of this tendency of the castrated or 

 mutilated flowers to fall soon after the operation. Although over 

 seven times as many treated flowers fell as remained normally attached 

 to the plant until maturity, still, except in the case of a complete 

 severance of the floral organs just above the ovary, a great majority 

 of the treated flowers remained on the plant for a period twice or 

 three times as long as is normal for treated flowers of any other 

 species or variety of Nicotiana in our cultures. Nearly 115 treated 

 flowers, most of them following castration, matured normal fruits, 

 ripened their seed and shed it from the dehiscing capsules. In nine 

 of the 112 cases tabulated in table 1, some seeds of normal size and 

 appearance were produced. The remainder of the seed produced 

 in these 112 instances was less than normal size but the great maj- 

 ority of it was normal in appearance — small, plump seed. I have 



