(1) The F₁ birds are entirely different from either parent and they are heterozygous for all the factor differences between the two types. The only alternative explanation for the intermediate condition of F₁ would be that each race carries one or more completely dominant factors. But the latter view is improbable because more of each parent type would then be expected in the F₂ generation. (2) In the F₂ generation the F₁ type is not as frequent as would be expected on the view that the heterozygotes could not be distinguished. E. BACK-CROSS OF F₁ ♀ TO SEBRIGHT ♂. It is possible to add, now, while this paper is passing through the press (June 1919), the results of a back-cross of 4 F₁ females to a Sebright male carried out during the summer of 1918. The birds being now mature their permanent colors are evident. Making the back-cross in this direction is much less advantageous than the reciprocal described above, because the Sebright contains most of the dominant color factors. The group of birds obtained appeared to be less variable in color than those from the other back-cross, and one can see at a glance that more of them approach the Sebright type; some quite closely. All of the males are hen-feathered, as expected. No evidence was found that two types of males exist, which would have been expected if the two types noted in F₂ had any hereditary significance. If, then, as the F₂ results suggest, two factors for hen-feathering are present both are dominant, and no genetic distinction is found between individuals in which one or both of the dominant factors are duplex or simplex. There were 9 adult hens and 10 hen-feathered cocks. An attempt is made below to refer them to their corresponding F₂ classes. F. REVIEW OF THE HEREDITY OF THE COLOR OF THE PLUMAGE OF POULTRY. In poultry there are perhaps more different colors and color-patterns than in any other species of domesticated animals. The genetic work has advanced far enough to show that many of the differences depend on Mendelian factors. It is probable that, in addition to the main factors, there are many contributory, minor, or modifying factors that give the finer details to “show birds.” It is generally supposed that the wild bird from which some at least of the domesticated races have come is _Gallus bankiva_ of India and Indo-China, or else one or another of its subspecies. In any case, the wild type of coloration is approximately known, since the known wild races are colored alike in all essential respects. Even were the color of the wild type not known, the original plumage could be deduced with some degree of probability from the atavism that appears when some of the races are hybridized. It is interesting to find that many of the new plumage characters are dominant to the wild type. The same relation also holds rather generally for other characters of poultry, such as the comb, etc.