Vol. 7, 1921 
GENETICS: SETCHELL ET AL. 
53 
true for the latifolia leaf -base type; one gave a fairly definite segregation 
into 3 latifolia: 1 sessilifolia with subsequent establishment of both types 
in constant derivative lines; and one population gave 3 latifolia: 1 sessili- 
folia. 
Sessilifolia selections behaved very simply. Of nine such selections, 
five bred true for sessilifolia, and the remaining four gave 3 sessilifolia: 
1 auriculata. 
Auriculata selections appear to breed true whenever tested. One popu- 
lation is an exception to this statement, but it was unfortunately not 
further investigated. Two other selections bred true for auriculata. 
An F 5 light pink auriculata derivative crossed with macropkylla (red 
sessilifolia) gave pink sessilifolia in F b and 133 pink sessilifolia: 40 pink 
auriculata: 53 red sessilifolia: 16 red auriculata in F 2 , a very close approxi- 
mation to an independent dihybrid expectation. 
On the basis of these facts we have been bold enough to offer provisionally 
the following formulation for the major differences in leaf -base characters : 
Ss, stenophylla versus sessilifolia, SS is long-petioled like angustifolia, 
ss broadly sessile like macropkylla. The heterozygote may possibly ap- 
proach an intermediate condition similar to latifolia. 
LI, stenophylla versus latifolia. SSLL is long-petioled like angustifolia; 
and SSll, short-petioled like latifolia, and with a distinct but not broad 
wing on the petiole. Latifolia is evidently a modified petiolate form. 
Aa, sessilifolia versus auriculata, ssAA has the broad clasping leaf-base 
characteristic of macropkylla; and ssaa the deeply constricted leaf -base 
with flaring auricles of auriculata. Auriculata is clearly a modified sessile 
form. 
As to the completeness of dominance in any of these factor pairs, we 
can say very little because of the difficulty of evaluating the effect of the 
residual genotype. Likewise the significance of the wing in latifolia 
or of the auricles in auriculata is not definitely established on account of 
the extreme genetic difference which existed between the original parent 
varieties. 
Tke Calycina-Virginica Series. — In the calycina-virginica (Maryland) 
series most of the attention was given to flower color and flower form. 
The flower color of calycina was red like that of macropkylla, and that of 
virginica was light pink like that of angustifolia. The results were in 
full agreement with those obtained from that series. The Fi was pink 
and F 2 gave 73 pink: 23 red, with the same variation in the pink class 
as that noted for the preceding series. Five red F 2 segregants gave 125 
F 3 plants all red-flowering. Of twelve F 3 families grown from pink segre- 
gants, three gave only pink-flowering descendants, and nine exhibited 
segregation into 3 pink: 1 red, the actual totals being 170 pink: 52 red. 
Calycina is characterized by the production of split hose-in-hose flowers. 
The calyx is strongly developed and petaloid and it is also deciduous in 
