PARTHENOGENESIS 9 



The cutting off of stigma and anthers in the 

 earliest stage of the young bud does not in the least 

 affect its development ; the tube grows to its full 

 length, the corolla expands to its full width before 

 withering, and there is no more delay in setting the 

 capsule than under normal selfing occurring on other 

 sprays of the plant. 



In these attempts to obtain parthenogenetic seed, 

 failures resulted in some of the hybrids, but these 

 were not more numerous than the failures from 

 attempts to self the same hybrids. 



The fact remains that parthenogenesis was dis- 

 covered in ten species, varieties and hybrids of 

 Nicotiana, and it is possible will be found in all of them 

 if the right period is chosen for the trial, i.e., when the 

 plant is beginning to go off its fullest bloom. iVmongst 

 the hybrids I found success more likely to attend a 

 test made at this stage, and also^when that test was 

 made on a spray which had already seeded one or 

 two of the lower blossoms. Amongst the species 

 and varieties this is not so necessar}^ In the 

 Tabaccums success was unfailing. 



AVhen we remember the wide geographical dis- 

 tribution of Nicotiana, the occurrence of partheno- 

 genesis in an Australian plant, hke N. Suavolens, in 

 the Tabaccum varieties, and in South American species, 

 points to the conclusion that it is an ancient character 

 in Nicotiana, and had developed in this genus before 

 the separation of the possible land connection between 

 Australia and South America. Or, if that conclusion 

 is questioned, we are led to infer that partheno- 

 genesis has arisen independently in different species 

 of the genus. 



