No. 557] PARTHENOGENESIS IN NICOTIAN A 299 



A N. paniculata plant treated with chloroform gave 

 two abortive seeds, but none of the other species produced 

 a seed. N. rustica var. texana, however, after two expos- 

 ures to acetone vapor underwent very marked morpho- 

 logical changes in the structure of the terminal blossoms, 

 both of the main and of the lateral stems. In other 

 words, the most exposed buds suffered the greatest in- 

 jury. As the ether, ethyl bromide, and check treatments 

 produced one blossom apiece which was similarly af- 

 fected, and no other species, even though treated with 

 acetone, was injured in the same way, indicates that the 

 N. rustica var. texana floral parts are somewhat un- 

 stable. This opinion is substantiated by Penzig who in 

 his Pflanzen-Teratologie cites observations where N. rus- 

 tica blossoms have been modified to such a degree that 

 the petals have turned green and where five blossoms 

 have been compressed into a common calyx. Perhaps 

 the presence of a small amount of chlorophyll in the 

 greenish yellow corollas is an indication of a close rela- 

 tionship of the petalous to the leafy condition. Even 

 though the N. rustica blossoms are easily modified, it is 

 very evident that the acetone vapor caused a disturbance 

 in the natural development of the floral organs, for the 

 two treated plants were affected in the same way and de- 

 gree. The calyxes, corollas and stamens were modified 

 markedly, while the carpels and pistils and most of the 

 stamens were usually normal in appearance. For in- 

 stance, in some cases the calyxes were fused together and 

 enlarged to such a size that they resembled distorted and 

 crinkled leaves. One blossom had three sepals fused to 

 the corolla and two sepals located one half inch below the 

 base of the blossom. The lower two had a node as dis- 

 tinct as any leaf on the branch, and within their axis were 

 borne two small buds, which lacked calyxes. One of the 

 upper three sepals also bore a similar naked bud in its 

 axis. It may be that in this case the acetone vapor 

 stunted the branches in such a way that many latent 

 buds were present in a very small space. The corollas 



