THE SEXUAL ORGANS. 235 



ing, very strong membrane, \" in thickness, constitutes both 

 the external tunic of the spongy bodies and also, in its ante- 

 rior half — as a thin lamella, partially broken up into separate 

 fibres and laminse — the septum between them ; it consists of 

 common fibrous tissue, like that of tendons and ligaments with 

 numerous, well-developed, fine, elastic fibres. Within it lies 

 the reddish spongy substance, consisting of innumerable fibres, 

 bars, and laminae united into a fine meshwork — the tra- 

 becule corp. cavernosorum ; and with its minute, rounded- 

 angular cavities, which anastomose on all sides, and, in life, 

 are filled with venous blood, the venous sinuses of the spongy 

 body — bears the most deceptive resemblance to a sponge. 

 All the trabecule, without exception, present precisely the 

 same structure. Externally they are covered by a simple 

 layer of intimately connected tesselated epithelium, the cells 

 of which frequently do not admit of being separated — the 

 epithelium of the venous spaces ; — to this succeeds the proper 

 fibrous tissue, which is composed, on the one hand, of almost 

 equal proportions of connective tissue and fine elastic fibres, 

 and on the other of smooth muscles, and in many, but by no 

 means in all the trabecule, encloses larger or smaller arteries 

 and nerves. The elements of the trabecular muscles are not 

 only at once distinctly recognisable from their wholly charac- 

 teristic nuclei, on the addition of acetic acid, but may also 

 be isolated in great numbers, and especially after treatment 

 with nitric acid of 20§, appearing as fibre-cells 0*02 — 0-03'" 

 long, 0-002 — 0-0025"' broad. 



The corpus cavernosum urethra (corpus spongiosum), is con- 

 structed essentially in the same way as that of the penis, 

 except that, 1. the fibrous membrane, which in the bulb also 

 forms the rudiment of a septum, is much thinner, less white, 

 and more abundantly supplied with elastic elements; 2. the 

 intertrabecular spaces are smaller, being smallest in the glans ; 

 3. and lastly, the trabecule are more delicate, and, beneath the 

 epithelium, richer in elastic fibrils ; having, however, in other 

 respects, the same structure as elsewhere. 



This is the place also to speak of the male urethra, which at 

 the isthmus is an independent canal, whilst at its commence- 

 ment and termination it consists merely of a canal of mucous 

 membrane, supported by the prostate and corpus cavernosum 

 urethra. The proper mucous membrane, beneath a longitudinal 



