There are various differences among individuals in the forms of round folds, and they may be divided into three types as follows: (i) the round folds, being lengthened laterally on both right and left sides of the white body, (ii) the round folds being somewhat lengthened lonigitudinally on both right and left sides of the white body, (iii) the round folds being of similar form to those of (ii) above described, and having, in addition, small folds attached laterally as if an accessory tissue to each of the round folds, so as to make forms of the round folds (i) mentioned above, as a whole. The accessory small fold forms boundary portion of the phallus along lymph fold, and most of the tissue of this small fold is quite similar to the tissue of the lymph fold, with an exception of tissue adjacent to the phallus, this tissue being of the same as phallus-tissue. From these morphological differences the forms of erected phallus are not one and the same in appearance, the round folds (i) and (ii) express heart-shape, and those of (iii)become large without changing their original forms.
Phallusの発生,形態並びに組織に就いては多くの報告がなされ(増井等, 1925; Hertwig, 1927; Dove,1928; 橋本,1930; 橋本,本間,1933; McDonald and Taylor,1933ect.),白色体(生殖突起)及び八字状褶襞より成ることが認められている.更に初生雛の生殖隆起の形態の差異に就いても詳細な観察が行われているが(増井・伊藤,1932)戚鶏の生殖隆起の形態上の差異に就いては充分なる報昔を見ない.筆者は“雄鵜の蕃殖生理に関する研究”中,成親に於ける生殖隆起の形態に就いて2~3の差異を認めたので,ここに記載せんとするものである.