on the human urethra. 
185 
connected by their origins and insertions with one another ; 
they all have a longitudinal direction, A muscular structure 
of this description, as far as I know, is not met with in any 
other part of the body. It is however to be observed, that 
there is no other instance in which fibres of such minuteness 
have been examined, and faithfully represented. 
There is a greater thickness of this muscular structure 
upon the upper, than the under surface of the urethra, which 
is still more evident, as it approaches nearer to the external 
orifice. The fasciculi are united together by an elastic sub- 
stance of the consistence of mucus. This muscular structure 
is represented in a longitudinal section of a portion of the 
corpus spongiosum urethrae, magnified fifteen times in di- 
ameter, The internal structure of these fasciculi is shown in 
PI. XXIII. Fig. 2, 3, magnified twenty-five diameters, and in 
Fig. 4, magnified fifty diameters. In this Plate the fasciculi 
are thickened in consequence of inflammation. Immediately 
beyond the muscular portion of the urethra, is the cellular 
structure of the corpus spongiosum. 
This mechanism, which forms the canal of the urethra, is 
very different from what it has hitherto been contemplated 
to be, and therefore a knowledge of it enables us to correct 
many errors that we had fallen into with respect to the actions 
of its parts, both in a healthy state, and when under the 
influence of disease. 
Till now it was believed, that either the lining of the 
urethra was composed of circular fibres, possessed of a power 
of contraction, or that it was immediately surrounded by 
such fibres ; and therefore, that the disease commonly known 
by the name of a stricture in the urethra, was produced by a 
