198 DR. F. WOOD-JONES ON THE 
cut off from the base of the genital tubercle and the urethra 
by the meeting of the outer genital folds: and in this way the 
anus becomes a separate orifice. 
The ingrowth and meeting of the outer genital folds take place 
first at the base of the genital tubercle at the site of their first 
prominence; and a constriction in their breadth in front of the 
anus marks this first union. At this stage the anus is triangular 
in outline, the apex of the triangle being directed towards the 
genital tubercle and corresponding with the primary ingrowth of 
the outer genital folds. In addition to this ingrowth, the outer 
genital folds have also become elongated, so that although the 
genital tubercle has increased greatly in length, it has become 
buried to a great extent beneath the overgrowing outer genital 
folds. Upon the portion of the genital tubercle which is still 
Text-figure 3, 
B 
A. Hairless nestling: 9,59 mm. 
B. External genitalia at this stage. 
exposed beyond the fused outer genital folds, the median raphé, 
formed by the union of the inner genital folds, is plainly visible. 
This raphé does not extend to the free extremity of the exposed 
genital tubercle. 
By the time the embryo is approaching full term and is 27 mm. 
long, the growth of the outer genital folds has become so pre- 
ponderant that the genital tubercle is practically hidden beneath 
