422 



THE EVOLUTION OF MAN. 



anus. Even before the appearance of this partition, in the 

 Pouched Animals (Marsupialia) and Placental Animals, a 

 conical papilla — the sexual protuberance (phallus, Fig. 329, 

 A,e, JB, e) — rises on the anterior part of the circumference of 



^- Ji 



i. 



1^1 



B. 



Fig. 329. — External sexual organs of the human embryo : A, neutral 

 germ (in the eighth week ; twice the natural size ; with cloaca) ; B, neutral 

 germ (in the ninth week ; twice the natural size ; anus distinct from the 

 urogenital opening) ; C, female germ in the eleventh week ; D, male germ 

 in the fourteenth week ; e, sexual protuberance (phallus') ; /, sexual furrow ; 

 hi, sexual folds ; r, Raphe (point of union of the penis and scrotum) ; 

 a, anus; ug, urinary sexual opening; n, navel-cord; s, tail. (After Ecker.) 

 Cf. Table XLIV., p. 431. 



the cloaca-opening. The apex of this is swollen into a knob 

 (the " acorn," glans). On the under side appears a furrow 

 (sulcus genitalis, f), and on each side of the latter a skin- 

 fold, or sexual fold (hi). The phallus is especially the organ 

 of the " sexual sense," and over it are distributed the sexual 



