320 SEMI-CENTENNIAL OF TORREY BOTANICAL CLUB 
made to illustrate the inheritance of height and probably the one 
made by Mendel for the same object. What is usually meant by 
geneticists, so far as the writer can learn, when discussing inherit- 
ance of height in peas, is really the inheritance of difference in 
internode length. Hence all short internode varieties or segre- 
gates, irrespective of actual height or number of internodes, are 
classed as dwarfs, while all long internode varieties or segregates, 
irrespective of number of internodes, are classed as talls. Classi- 
fied in such a manner, the Е, population from such a cross as de- 
scribed above would have approximately 3 tall (long internodes) : 1 
dwarf (all short internodes). The long internode half-dwarfs would 
be called talls, while the half-dwarfs with short internodes would 
be called dwarfs (see Bateson et al., 7о5; Lock, 705, 08; Laxton, 
'o6). 
Crosses between half-dwarfs with long internodes and true 
dwarfs gave half-dwarfs іп Е, and approximately 3 half-dwarf 
(long internodes) : т dwarf (short internodes) in Е in the writer's 
experiments. Bateson (705) commonly obtained intermediates in 
F; from crosses between half-dwarfs (presumably short internodes) 
and dwarfs. 
The simplest interpretation of the above data involves the 
presence and absence of at least five genetic factors for height, 
two of which primarily determine the differences in internode 
length and three of which are largely responsible for the hereditary 
differences in number of internodes. These with their expression 
may be represented as follows: 
Le = long internodes 
Le; = very long internodes 
= 20-40 internodes 
Ti = 40-60 internodes 
Т» = 20-30 internodes 
Absences 
le = short internodes 
t = 10-20 internodes 
Le and T have been referred to in previous numbers of this 
series (White, ’17 a and b), Le being the factor isolated by Mendel 
and confirmed by many later workers. Т is referred to by Keeble 
