38 R. A. EMERSON 
and 49 dilute purple where the expected numbers were 163 and 54, respec- 
tively — a deviation of 5 + 4.3. 
It is seen, then, that in every case the F; progenies of F. purple plants 
were of color types expected on the basis of the three-factor hypothesis, 
and that the F; distributions within any group were in close agreement 
with expectation. It is particularly noteworthy, however, that not all 
types of F; behavior were observed, and that the distribution of the 
progenies of the thirty-five F2 plants tested was in rather imperfect agree- 
ment with expectation. Thus, no F2 purple plant bred true in F3 where 
one such plant was expected, and none gave progenies of purple and 
brown only where at least two with such behavior were expected.. It 
has already been pointed out (page 35) that eight classes of behavior of 
F, purples are looked for, and that any twenty-seven F, purple plants 
should be distributed with respect to their F; behavior in the relation 
1:2:2:2:4:4:4:8. The actual and theoretical distributions are compared 
as follows: 
Observed ?su5.5.0: 0 5 2, 0 5 7 7 ‘9 35 
C@alculated=s.s2< 3 2.6 2.6 2.6 OBZ 5B Ae iat 35.1 
Ditterences seem oe —1.3 +2.4 0.6 2.6 0.2 4+1.8 +1.8 —1.4 —). 1 
While mere inspection of the above comparison might suggest poor agree- 
ment between theory and observation, nevertheless P=0.36, indicat- 
ing that such deviations as occur might be expected in more than one 
out of three trials, which is not a bad fit. So far, therefore, the avail- 
able data are in fair accord with the three-factor hypothesis. 
- Before taking up a consideration of the F; behavior of other F»2 color 
types, 1t will be well to consider briefly the F, behavior of F; purple plants. 
Only one F; purple of the lot having all six color types (table 8, group 1), 
comparable to F, purples, was tested in Fi. This one plant gave an F4 
with the four color types Ia, Ifa, V, and VIa. 
Only eight other F; purple plants were tested in F;. All these belonged 
to the lot consisting of color types Ia, Illa, V, and VIb (group 4, table 8). 
The F, purple plants giving rise to this group are assumed to have been 
of the genotype Aa@Bb PI Pl. The Fs; purple plants should therefore 
have been of four genotypes and should have given F, behavior as 
follows: 
