The erection of rudimentary copulatory organ or phallus of the cock is brought about by the similar cause to the erection of penis in the drake. Namely, the lymph, which is separated from blood copiously in the tissue of the "Gefassreichem Korper" (Liebe, 1914), fills up the "Lymphbildungsraum" (Liebe, 1914) and then runs off from the hind opening of it into the phallus through the lymph sinuses communicating the phallus with the "Gefassreichem Korper". Lymph pressure in the phallus increases greatly, and thus the erection of phallus is caused. The lymph in the phallus runs off, in a short time, e. g., a few seconds, through the same passage flowing backward from phallus to "Gefassreichem Korper", and finally runs into the lymph duct lying along the A. pudenda interna; then the phallus regains its original quiescent condition. So far as the cock responds to sexual impulses by means of abdorminal manipulation, the phallus erects every time, some birds continuing erections 6 times or more. The most conspicuously swelling portions in the phallus are the labia minora (so called round-folds), especially their anterior parts, so that the phallus thrusts out back- and downwards, covering the ventral wall of the cloaca. This exposition of the phallus is also helped by the relaxation of M. retractor penis posterior and the swell of lymph-folds. The erected phallus in this manner, both sides of labia minora are in contact with each other and forms the longitudinal groove on the contact portion, and roughly heart-shaped on the whole. The critoris lies on the lowest portion of it. During ejaculation, the papillae approach to the swelled roundfolds, and the semen is ejected in front of the outer portion of the round-folds. The ejected semen flows along, both right and left round-folds, joining at the upper part of the longitudinal groove mentioned above, and then runs down along the groove. Thus the ejected semen is easily ejaculated out of the body from the cloaca; thus the erection of phallus may help the mating of fowl, but the phallus is not necessarily indespensable for coitus. Lymph-folds swell up with the lymph which cause the erection of the phallus, therefore, they are considered by the writer, to be accessory organs of the phallus.
雄鶏の生殖隆起が交尾に当たり勃起することは,增井,橋本,大野(1925),芝田外氏(1938)により記載されて居り,勃起した生殖隆起の形態はBurrows and Quinn(1937)及びKaupp (Burrows and Quinn,1937,に依る)に依つて報告されているが,勃起の機構に就いては筆者の知る限り認むべき報告がない.本論文はこの点を究明する為に行はれた実験結果を報告せんとするものである.本研究は引続き丹下教授の指導の下に行はれた.