Studies of Teratological Phenomena. 121 



8. Under five distinct geographical and topographical environments, 

 the characteristic expression of the fasciated race has remained quali- 

 tatively, but not quantitatively constant. One of these environments 

 was characterized by impoverished soil, general cultural neglect, and 

 over -crowding, but the plants, though dwarfed in the size of their 

 leaves and stems, had flowers and stems of the prescribed abnormal 

 type. From comparisons in leaf number, between individuals grown 

 under different field conditions, it is believed that environment, especially 

 the factor weather, is able to change their variability in number per 

 plant. The change in number of floral segments may also be associated 

 with climatic factors. 



9. The 300 — 309 race is probably not as well "adapted" to 

 different environments, as is the parent race from which it mutated. 

 The few seed set by the original mutant might indicate that had it 

 arisen under natural conditions, its ability to persist would have been 

 very problematical. In the Harvard University cultures, the race is 

 very fertile, though falling short in this respect when compared with 402. 

 This means, that on a basis of fertility, the latter would be the more 

 successful competitor in the struggle for existence. The modifications 

 produced by a combination of the factor A, and certain environmental 

 conditions would further cause this variety to be a losing competitor in 

 the struggle with the normal, as under extremely favorable environmental 

 conditions (for the factor A) ver}^ few flowers would develop and mature 

 seed. As far as roots and general plant vigor are concerned, when 

 placed under ordinarily favorable tobacco growing conditions, one race 

 is no better equipped for existence than the other. Under many tropical 

 environments, I have no doubt that the race, as now grown, would 

 persist and compete successfully with many other plants for existence, 

 if selfed seed were sown in such places. 



10. The results secured from the selection experiment are only 

 indicative and possibly may be interpreted as favorable to the idea of 

 the creative power of selection. I prefer to interpret them as indicating 

 the inability of selection to modify the fasciated character, so as to 

 produce eventually a normal. The data are not conclusive, however. 



11. The data from crossing a fasciated plant with a normal (402) 

 plant demonstrated in a clear manner that the two races apparently 

 differed only in the possession of a single unit factor A. The Fi was 

 intermediate in character and the F2 gave abnormal (AA), heterozygous 

 (Aa), and normal (aa) segregates in the ratio of 1 : 2 : 1 or 3 abnormals 



