70 R. A. Emerson 
is taken almost wholly from Dr. Anderson’s records, and the conclusions 
derived from it are his. It is with Dr. Anderson’s permission and at 
his suggestion that, for the sake of completeness of this account of the 
inheritance of plant. colors, his results are here presented. 
A cross of a weak purple Ib with a homozygous dilute purple IIIa 
resulted in 25 weak purples only, while a cross of another weak purple 
with a homozygous dilute purple, a sib of the plant used in the first cross, 
gave 63 weak purples and 53 dilute purples. Two of the F; weak purples 
were backcrossed to dilute purples, and a third to dilute sun red. The 
result (table 34, group 1, page 145) was 141 weak purples and 163 dilute 
purples, a deviation of 11 + 5.9 from equality. .Five crosses of weak 
purples with dilute sun reds gave a total of 32 weak purples and 25 dilute 
purples, a deviation from equality of 3.5 + 2.5, while two other such 
crosses gave 29 weak purples only. Evidently these weak purple plants 
differed from dilute purples by a single factor pair. This pair could not 
have been Pl pl, for the crosses of weak purple with dilute purple, A b Pl, 
gave the same results as those with dilute sun red, A b pl. This leaves the 
possibility that Bb or some unknown factor pair was concerned. 
Three crosses of weak purple Ib with purple Ia resulted in 52 purple 
plants. A single cross of weak purple with sun red Ila gave 18 purples. 
Evidently both purple and sun red carry some factor that acts to change 
weak purple to purple. Unfortunately, no later generations of any of 
these crosses were grown, but it 1s evident from the F,; results and from 
what is known of the interrelations of purple, sun red, and dilute purple 
that the dominant factor B, common to both purple and sun red, is con- 
cerned in the change from weak purple to purple. Since the crosses of 
weak purple with dilute purple, A b Pl, and with dilute sun red, A 6 pl, 
gave no purples, while crosses of weak purple with purple, A B Pl, and 
with sun red, A B pl, gave purple, the Pl pl pair is not concerned in the 
difference between weak purple and purple any more than in that between 
weak purple and dilute purple. These results, however, do not exclude 
the possibility that weak purple may be A b Pl, like dilute purple, with 
the addition of some unknown dominant modifying factor. 
A single weak purple plant, which was, so far as known, unrelated to 
the weak purples considered above, when crossed with two unrelated 
dilute sun reds gave progenies consisting of 15 weak purples and 13 weak 
sun reds. Seven progenies of these F; weak purple plants backcrossed 
