263 
merely as an extension of the urethra. Sections through it, however, 
show that it is a more complex structure. Fig. 2 represents one of 
these sections, taken at a 
point about a quarter the 
length of the appendage from 
its tip. In the centre is the 
urethra bounded by a much 
folded wall of epithelium. 
Outside this is connective 
Fig. 2. Transverse section 
through filiform appendage, about 
a quarter its length from the tip, 
x 45. Bl. V. blood-vessels, Ep. Ur. 
epithelium bounding urethral cavity, 
Fibr. Cart. fibro-cartilage body, Int. 
integument, Musc. muscle layer, Ur. 
urethra. 
tissue, a great part of which contains numerous and large blood-vessels 
and is clearly erectile in character. This may be regarded as forming 
an extension of the corpus spongiosum into the appendage. Muscular 
tissue is also present, especially towards the periphery, where there 
is a well-marked layer of circular muscles. There are also a pair of 
fibro-cartilage bodies placed one on each side of the urethra and sur- 
rounded by erectile tissue. They are placed nearer the inferior than 
the upper surface of the appendage. Outside the muscle layer is the 
integument which consists of a stratified epithelium, which is closely 
similar in appearance to that bounding the urethra. This similarity 
passes into identity at the end of the organ where the urethra opens 
out, the two epithelia being here perfectly continuous. The stratified 
character of the epithelia best seen in hematoxylin preparations is not 
well shown in the figure which was drawn from a section stained with 
methyl blue and eosin. In the latter the epithelia are stained red, 
and the muscular and erectile tissue blue, while the fibro - cartilage 
bodies are coloured by both stains. 
The filiform appendage except for slight differences in the thick- 
ness of the fibro-cartilage bodies and in the foldings of the epithelial 
wall of the urethra presents the same structure throughout the greater 
part of its length. Thus the fibro-cartilage bodies are compact and 
there is a clear line of demarcation between them and the surround- 
ing tissue. On approaching the proximal end, however, they tend to 
become irregular, and fibro-cartilage makes its appearance at separate 
points in the connective tissue. Sections through the rounded knob, 
