THE PENIS. 89 



bly, is the part described by Winslow as the inferior pro-static 

 muscle; which he asserted to arise on each side of the mem- 

 branous part of the urethra, and to be inserted into the corres- 

 ponding branch of the pubes near the symphysis. The mem- 

 branous part of the urethra does not get into the end of the oulb, 

 but penetrates it from above, half an inch or more occasional- 

 ly, from its extremity, just below the junction of the crura of 

 the corpus cavernosum. 



The canal varies in its dimensions : at its commencement, 

 which is synonymous with the neck of the bladder, it is large; 

 it then contracts at the back of the caput gallinaginis, and im- 

 mediately enlarges in the fore part of the prostate, at the sides 

 of the caput. The membranous part is small; the canal then en- 

 larges in the bulb. In the body of the penis the canal is suc- 

 cessively diminished, till it comes almost to the glans, when it 

 is so remarkably enlarged again as to get the name of Fossa 

 Navicularis,- it terminates, finally, by a short vertical slit at 

 the extremity of the glans. 



The canal of the urethra is formed of a very thin mucous 

 membrane, on the outside of which is a dense filamentous cel- 

 lular substance possessing great extensibility, contractility 

 and elasticity. The mucous membrane has great vascularity, 

 and its veins are so superficial that they frequently bleed freely 

 upon the introduction of an instrument into the bladder, it is 

 also very sensitive. The cellular coat on its outside, whereby 

 it adheres to the spongy structure, contracts sometimes in such 

 a manner that circular fasciculated ridges simulating the pre- 

 sence of circularjrmscular fibres are seen shining through the 

 mucous coat, though when the mucous coat is peeled off this 

 arrangement disappears. 



In the whole length of the canal there are two folds or lines, 

 one above, and the other below ; and in the membranous and 

 spongy portions, excepting the fossa navicularis, longitudinal 

 folds of the mucous membrane also exist, which are effaced by 

 distention. The fossa navicularis sometimes exhibits in the 

 contracted penis, hardened in spirits of wine, very superficial 

 folds of the mucous membrane almost transverse, in the nar- 

 row depressions between which we see the orifices of very fine 

 mucous follicles. 



In the upper part of the canal there are a great many mucous 



