1915] Goodspeed: Parthenogenesis, Parthenocarpy, Phenospermy 255 



No success attended a small number of attempts to cut Avith a razor 

 directly across the whole flower, severing corolla, filaments and style 

 (cf. Thomas, loc. cit). Such treatment caused the buds to fall within 

 three days. The number of simple castrations far exceeded either of 

 the other two types of treatment. 



The plants of "Nic. tabacciim Cuba" began to flower during the 

 first week of September, 1914, and were still in flower, though very 

 feebly, early in February, 1915. The castrations and mutilations 

 were begun in the case of plants 1 to 75 on the day that the first 

 flower of the terminal inflorescence opened, or as near that date as 

 possible. As the plants came more fully into flower as many buds 

 as possible were treated. For the first month, flowers on each suc- 

 ceeding bald sucker were operated upon almost as soon as the first 

 flowers were open. Later in the season time did not permit any such 

 close following of the plants. The nineteen plants, 76 to 95, were 

 growing some fifty feet aw^ay from the rest and most of them were 

 left untouched until they were "beginning to go off their fullest 

 bloom" (Thomas, loc. cit., p. 5). These nineteen plants were set out 

 into the field somewhat later than the rest and came into flower 

 somewhat later also. When their flowers were first operated upon, 

 the terminal inflorescence and many of the upper laterals bore many 

 partially matured seed-capsules. No seed was shed from untreated, 

 unbagged flowers on any of the plants imtil the last week in October. 



The bags which evidently contained seed were taken from the 

 plant at once. In practically all cases the seed had been shed from 

 the capsules which had opened normally. The cleaning of the seed 

 was done with the utmost care and I cannot feel that any contamina- 

 tion could have occurred in this connection. As a result of the clean- 

 ing, it was evident that a very considerable number o-f castrated and 

 mutilated flowers had given seed, a part of which was apparently 

 normally matured and the majority of which consisted of nothing 

 but empty seed-coats. It was out of the question to attempt germina- 

 tion tests of all the seed thus available. According to our usual method 

 of making such tests with tobacco seed (Goodspeed, 1913), the number 

 of seeds to be handled would in this case have approximated 10.000 

 and probably the germination of double that number would have 

 been found to be neces.sary. It was thus judged best to adopt the 

 following method for determining which of the packets of seed con- 

 tained only empty seed-coats and which contained any apparently 



