318 SEMI-CENTENNIAL OF TORREY BOTANICAL CLUB 
" half-dwarfs" сап be separated into at least two genetic types. 
One of these is illustrated by the examples of half-dwarf already 
mentioned— Velocity, First of All, and Express. These have 
long internodes, similar to the 40-60 and 20-40 long internode 
talls, but fewer in number, ranging between 10-20. The other 
type of half-dwarf has short internodes, similar to the short 
internodes of the true dwarfs. This type is illustrated by the 
variety Dwarf Gray Sugar, with internodes ranging in number 
from 20 to до. Тһе variety Autocrat, as studied by Keeble and 
Pellew (то), probably also belongs in this category. 
Half-dwarfs with long internodes crossed with short internode 
half-dwarfs give long internode talls in Е, and long internode talls, 
long internode half-dwarfs, short internode half-dwarfs, and true 
dwarfs, approximating a 9:3:3:1 ratio in Е. Similar results 
from such a cross, so far as the writer can judge, have been ob- 
tained by Keeble and Pellew (то), although they have given them 
a somewhat different interpretation (see also Lock, 'os). Half- 
dwarís of each type crossed with similar half-dwarfs, as expected, 
breed true іп Е,, Fz and later generations. Half-dwarfs of the 
short internode type crossed with the 20—40 long internode tall 
type give in Е, talls with long internodes, which іп Е produce а 
population approximating 3 talls with long internodes : І half- 
dwarf with short internodes. The difference in height between 
such talls and such half-dwarfs is due largely to internode length, 
the number of internodes in each type being approximately the 
same. Half-dwarfs with long internodes crossed with talls with 
long internodes (20-40 type) give talls in F, and populations 
approximating 3 talls : т half-dwarf in Fs, both, of course, with 
long internodes, the difference between them in this case being 
due to internode number. 
True dwarfs (6 inches to 3.5 feet high) in peas all have short 
internodes, ranging f om 8 to 20 in number. Laxtonian, Nott's 
Excelsior, and several French varieties obtained through the 
courtesy of Phillipe Vilmorin are excellent examples. When 
crossed with the various types of talls, the F; generation always 
consists of talls with long internodes, although large number of 
internodes may not be completely dominant over small number 
of internodes in certain cases, e. g., Pois nain à châssis, trés hâtif 
