. Genetics in relation to agriculture. Livestock; Heredity; Variation (Biology); Plant breeding. 214 GENETICS IN RELATION TO AGRICULTURE Shull's conclusions are further supported by evidence from the inheritance of a sex-Hnked character in Lychnis, the only sex-linked character thus far known in plants. The character in question is that of narrow rosette leaves as distinguished from the normal broad type of leaf, and there are other associated character differences (Fig. 96). The narrow-leaved form, called angustifolia, was discovered by Baur as a single male mutant individual, a significant f
. Genetics in relation to agriculture. Livestock; Heredity; Variation (Biology); Plant breeding. 214 GENETICS IN RELATION TO AGRICULTURE Shull's conclusions are further supported by evidence from the inheritance of a sex-Hnked character in Lychnis, the only sex-linked character thus far known in plants. The character in question is that of narrow rosette leaves as distinguished from the normal broad type of leaf, and there are other associated character differences (Fig. 96). The narrow-leaved form, called angustifolia, was discovered by Baur as a single male mutant individual, a significant fact when taken in connection with its subsequent behavior. The factors in this case are B for the broad-leaved condition and h for the narrow-leaved condition. Crosses between typica females (BX){BX), and angustifolia males (bX)Y. Fig. 96.—Adult rosettes of Lychnis dioica; on the left a plant of the normal form, typica; on the right a plant of the narrow-leaved form, angustifolia. (After Shull.) gave in Fi all broad-leaved plants (BX) (bX) females and (BX) Y males. Heterozygous broad-leaved females {BX){bX) mated to broad-leaved males {BX)Y gave all broad-leaved females, and approximately equal numbers of broad-leaved and narrow-leaved males. Hermaphrodites were also found to behave the same way with respect to the factor B as did the males, which confirms the hypothetical relation supposed to exist between hermaphrodites and females. The evidence clearly indicates the existence of sex-linkage of the kind called for on the assump- tion that Lychnis exhibits the XY tjqie of sex-inheritance. Secondary Sexual Characters.—Secondary sexual characters are those which appear as an invariable or almost invariable accompani- ment of a particular sex in most animal forms. They include many diverse things, such as the antlers in male deer, the horns of the males of some breeds of sheep, the mane of the lion, the power of song of many Digitized by Microsoft®. Please note that these im
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