90 "White. 



was common. Great variation in the staining properties of the 

 preparation was noticeable, this probably resulting from physiological 

 abnormalities. The chromosomes of a mother-cell were either increased 

 in number by abnormal division or nuclei divided and never separated. 

 In one case 51 chromosomes were counted in a reduction phase, and 

 from the manner of their occurrence, it would seem there was no other 

 interpretation than of increase in number through a division of only 

 part of the chromosomes of this cell. The cell was in a state of 

 disintegration. Other cases occurred in which there were 30 where 

 only 24 should have been counted. Irregular divisions and lagging 

 chromosomes were not infrequent. The chromosomes of Nicotiana are 

 small, though very distinct in the maturation stages, but in cases where 

 abnormal conditions prevailed, one could not always be certain they 

 were counting heterotypic or homotypic chromosomes or both, owing to 

 premature division of some of the heterotypic chromosomes. Increases 

 in number were rare, but many of the other abnormalities mentioned 

 were common. Supernumerary pollen grains such as occur in Hemerocallis 

 were never found. Divisions of chromosomes in somatic cells on account 

 of their size, were studied with difficulty, and gave no data. Cytological 

 observations on maturation in the gynoecium were only superficial as 

 compared with those of the anthers. No special abnormalities in the 

 reduction divisions were noted in the few sections examined, but a 

 small percentage of the embryo-sacs appeared to be abortive. 



From data taken in connection with the floral leaf counts, I 

 should judge the contabescent anthers to be from 4 — 5 per cent, but 

 such data probably gives too low an estimate, because one cannot be 

 always certain that an anther, externally normal, represents the same 

 internal state. 



Summarizing, one may say that although these abnormal cellular 

 conditions are strictly inherited, their morphological aspects closely 

 resemble the cytological changes produced in plants through external 

 stimuli, such as fungi, insects and chemicals, after the manner in 

 which these have been described by Molliard (1897), and others. 

 Gregory (1905) described similar phenomena in the case of the abortive 

 anthers of sweet peas, though in this case as in Nicotiana^ the pheno- 

 menon was of strictly hereditary nature. 



Fasciation in Nicotiana is comparatively rare, as somewhat extensive 

 search through the literature brought to light only a few cases of floral 

 fasciation in Nicotiana affinis (alata) (deVries). 



