178 BOTANICAL GAZETTE [MARCH 
a character-complex which I believe to be the least affected by 
external conditions of any character that shows marked varietal 
differences. This character-complex is corolla size. The fact that 
corolla size is so comparatively constant under all conditions attend- 
ing development has such a definite bearing on some broad ques- 
tions of organography that it merits separate discussion. On this 
account, the liberty of asserting the truth of the statement with 
only the following data in its support is requested. 
During the past four years, I have grown about 20 species of 
Nicotiana in considerable numbers. They have been grown under 
very diverse conditions. Some have been starved in four-inch pots, 
others have had the best of greenhouse treatment; some have had 
poor field conditions, others have had all field conditions practically 
at their best. The height of the plants, the size of the leaves, and 
similar size complexes have varied enormously, but the size of the 
corollas has scarcely varied at all. For example, plants of Nico- 
tiana silvestris Speg. and Comes grown to maturity in four-inch 
pots produced no leaves longer than 7 in. On the other hand, 
sister plants of the same pure line produced leaves 30 in. long in the 
field. Both series, however, produced flowers with the same 
length and spread of corolla. Furthermore, cuttings from 20 of the 
field plants reported in this study were rooted and grown in small 
pots in the greenhouse. Their blossoms were the same size as 
_ those of the field grown plants from which they came. 
The material used in this particular experiment consisted of pure 
lines of two Nicotiana types that are generally treated as distinct 
species (pl. VI). The male parent was Nicotiana alata grandiflora 
Comes, it being the plant called Nicotiana affinis by horticulturists. 
Three lots of it were under observation; one was obtained from 
Italy and the other two from the United States, but the original 
sources of the strains are unknown. These three lots were alike, 
and in successive generations were constant in their characters. 
They accorded perfectly with Comes’ description and were remark- 
ably narrow in their variability. The female parent I have called 
Nicotiana forgetiana, Hort. Sand., and thereby hangs a tale. 1 
found in the Gray Herbarium of Harvard University a sheet from 
near Los Angeles, California, marked Nicotiana clevelandii Gray. 
