76 EXPERIMENT STATION EECORD. 



The source of diminishing potency is illustrated in the case of rumploss fowl. 

 '• Here a dominant condition was originally mistaken for a recessive condition 

 because it never fully showed itself in Fi and F^.. Nevertheless, in related indi- 

 viduals the condition is fully dominant. We thus get the notion that a factor 

 that normally tends to the development of a character may, although present, 

 fail to develop the character. Dominance is lacking through impotence." 



"The last term of the series is seen in the wingless cock which left no wing- 

 less offspring in the Fi and F:. generations. In comparison with the results 

 gained with the rumpless cock, winglessness in this strain is probably dominant 

 but impotent." 



The inheritance of booting, or the feathering on the feet, was studied with 

 bantam Cochins of 2 varieties, a bantam Darlv Brahma, and with Silkies. It 

 appeared to he blended and without segregation, but by the aid of the principle 

 of imi)erfect dominance, the apparent blending was found to follow segregaticm. 

 Booting was controlled by a dominant -inhibiting factor which varies greatly 

 in potency. The coefficient between average parental and filial grades was 

 found to be — 0.17±0.1.3, which can be interpreted to mean that in a homogenous 

 assemblage of families there is no correlation between the grade of booting of 

 parents and offspring. By the aid of the same principle in crosses between the 

 embryonic open condition of the nostril, exhibited by the Polish and Houdau. 

 and the more advanced condition of the narrow nostril, the nostril height way 

 found to be controlled by an inhibiting factor that stops the overgrowth of the 

 nasal flap and produces the narrow nostril. 



" The crest of fowl receives especial attention as an example of a character 

 previously regarded as simple but now known to comprise two and probably 

 more factors — a factor for erectness, one for growth, and probably one or more 

 that determine the restriction or extension of the crested area. 



" The direction of lop of the single comb is an interesting example of a char- 

 acter that seems to be undetermined by heredity. In this it agrees with numer- 

 ous right and left handed characters. It is not Improbable that the character 

 is determined by a complex of causes, so that many independent factors are 

 involved. 



" A series of studies is presented on the inheritance of plumage color. It is 

 shown that each type of bird has a gametic fornmla that is constant for the 

 type and which can be used with success to predict the outcome of particular 

 combinations. New combinations of color and ' reversions ' receive an easy 

 explanation by the use of these factors. The cases of blue, spangled, and barred 

 fowl are shown also to contain mottling or spangling factors." 



The difficulty of changing a breed is illustrated by 2 experiments. The aim of 

 the first experiment was to increase the red in Dark Brahmas liy crossing with 

 Game, but was met with wholly unexi»ected prompt success, though not in the 

 way anticipated. The result was not due to selection but to the recombination 

 of the factors necessary to make the Game plumage coloration. In the second 

 experiment an attempt to produce a new buff race from the (Jame fowl by means 

 of selection has so far resulted in failure. 



A bibliography of the literature is appended. 



Some factors influencing' the vigor of incubator chickens, J. H. Stewart 

 and H. Atwood (West Virginia Sta. Bui. 12.'i, pi). 21-Ji5). — Experiments ai*e 

 I'eported on the effect of the age of the parents upon the vigor of chickens, on 

 the airing and cooling of eggs during incubation, and on the use of moisture. 



Eight comparative tests were made on the fertility and hatchability of eggs 

 from pullets and old hens. As far as stated, the only breed of fowl used was 

 the White Leghorn. The eggs and chicks were treated as uniformly as possible. 



