40 R. A. EMERSON | 
It should not be forgotten that, while a very poor fit of observation to 
hypothesis, as measuted by values of P, throws doubt upon the correct- 
ness of the hypothesis, it does not follow that a good fit proves the 
hypothesis to be true. This is particularly true where small numbers 
are dealt with. It will be recalled in this connection that, owing probably 
to the small numbers tested, no F. purple has been found to breed true in 
F, and none has been found to give only purple and brown offspring. 
It has been shown, however, that purple plants of the genotype 
AaBB Pl Pl exist, since one F; purple threw only purple and brown 
plants in Fs. Moreover, one of these F; purples repeated this behavior 
in Fs. Similarly it can be said that purples of the genotype A A B B Pl Pl 
have been recovered from the crosses under consideration, for two F, 
purple plants of the lot composed of purples and dilute purples (group 2, 
table 9), when backcrossed to green, gave 18 purple plants and no other 
types in the next generation, and one of these two F,; purples, when crossed 
back to dilute sun red, gave 34 purple plants. Two other purples of 
the same F; lot, when similarly crossed, gave both purple and dilute purple, 
23 of the former and 18 of the latter. Purple plants of all the expected 
genotypes have therefore been recovered in one or another generation 
from F: to F; from the original crosses of purple x green and dilute sun 
red x brown. Moreover, these genotypes have been found in numbers 
not far from what might reasonably be expected considering the relatively 
small numbers tested. It now remains to inquire into the F3 and later 
behavior of F2 color types other than purple. 
Later behavior of Fz sun red ITa—Sun red plants of Fo of the « crosses 
purple x green and dilute sun red x brown are expected, in accordance 
with the three-factor hypothesis, to be of four sorts with respect to their 
behavior in F3, as follows: 
F; color types 
F,2 genotypes 
Sun red ed Green 
Ila Sune Via, ¢ 
a 
i AA BiB pl pte eae sac ne Ee ee I Metricaut | sookooene 
2 HAAS Bibl Divine See ceo ae So ee 3 1 iseees eee 
Di AG BiB pliplisssc': stipes oyse series isi is en On eee 3: [|G scleee eee 1 
A ARGS BSD spl Dats no Aery Rin ose eo ee ee 9 3 4 
