PENIS. 
runs forwards by the side of the septum pec- 
tiniforme, distributing many branches in its 
course, which ramify in the parietes of the 
venous canals. 
The arteria dorsalis penis may be regarded 
as the continuation of the internal pudic, after 
the latter has given off the arteria corporis 
cavernosi. It commences opposite the junction 
of the crura penis, and piercing the anterior 
layer of the deep perineal fascia, ascends to 
the groove upon the dorsum penis. In this 
groove it runs forwards to the base of the glans, 
where it divides into several branches, which 
enter the substance of that body and are distri- 
buted to its structure. The arteria dorsalis is 
separated from its fellow by the dorsal vein, 
and gives off numerous branches in its course 
to the fibrous structure of the penis and inte- 
gument. 
The veins of the penis correspond with the 
arteries which they accompany in their efferent 
course. The vene corporis bulbosi and vene 
corporis cavernosi, issuing respectively from 
the bulb and crura penis, take the course of 
the internal pudic artery, and constitute the 
internal pudic veins. At the root of the penis 
these veins communicate with the dorsal vein. 
The dorsal vein commences by numerous 
largé branches, the chief of which issue from 
the base of the glans beneath the corona, and 
form by their communications a considerable 
plexus on the anterior part of the corpus cayver- 
nosum, the,others being the veins of the prepuce 
and integument. The union of these veins 
constitutes two trunks of equal size, which, 
afier running side by side for a short distance, 
unite and form the dorsal vein. The dorsal 
vein in its course towards the root of the penis 
passes beneath the aponeurosis of the erectores 
muscles, together with the attachment of the 
suspensory ligament, and after piercing the deep 
perineal fascia, divides into several branches 
which join the prostatic and vesical plexus. 
It receives in its course several large branches 
from the corpus spongiosum, which curve 
around the corpus cavernosum in order to reach 
it, and communicates at the root of the organ 
with the deep veins of the penis. The dorsal 
vein is situated in the middle line of the groove 
of the dorsum penis, having its corresponding 
artery at either side, and being covered in by 
the fascia penis and conjoined aponeurosis of 
the erectores penis muscles. It is this relation 
to the fascia penis and aponeurosis of the 
erectores that enables the latter to compress the 
vein forcibly against the dense fibrous coat of 
the corpus cavernosum, and thus intercept the 
current of venous blood. 
The question of the ultimate arrangement 
of the bloodvessels in the substance of the 
penis leads to enquiry into the nature of erec- 
tile tissue, a subject to which a separate article 
has been devoted in the earlier pages of this 
work, and to which I must now refer my 
reader. From my own investigations into the 
structure of this tissue in the corpus caverno- 
sum and corpus spongiosum, I have come to 
the conclusion that the arteries ramify and ter- 
minate in capillaries as in other parts of the 
917 
body, and that these latter very speedily be- 
come dilated veins. In the distribution of the © 
veins the only peculiarity of this tissue exists ; 
these by their tortuous windings form an in- 
extricable plexus, which fills the whole area of 
the fibrous tunics of the corpus cavernosum 
and spongiosum, and constitutes their com- 
ponent substance. In this plexiform aggre- 
gation of veins, the walls of the vessels so 
closely approach as to leave between them 
only so much connecting tissue as serves for 
the ramification of the arteries and nerves of 
the organ, and for the passage of the fibrous 
trabecule and fibres of the contractile tissue. 
It follows from this arrangement that the arez 
of the veins bear a much greater proportion to 
the bulk of the tissue than do the septa between 
them, and, consequently, that if a section of 
the corpus cavernosum be made, its parenchyma 
will have the appearance of a cellular net- 
work, an appearance that is rendered much 
more striking when the penis has been inflated 
and dried. It is obviously this appearance of 
the parenchyma of the corpus cavernosum 
that has gained for it the character of being 
composed of cells, and in truth, as far as the 
plane of the section is concerned, the portions 
of venous canals which open on the surface 
have all the attributes of divided cells. Ac- 
cording to the position of the veins at the point 
of section, the cell in one spot is shallow and 
small, in another it is lengthened, either in the 
longitudinal or in the transverse direction of 
the axis of the corpus cavernosum, and ina 
third, again, the apparent cell is irregular in 
form, from the conjunction at that point of two 
or more veins. If, in the next place, we turn 
our attention to the septa of the apparent cells, 
we shall meet with spots in which from the 
close assemblage of the veins the septum has 
the appearance of a star giving off a number 
of thin lines in a radiated direction to form 
partitions between three, four, or five veins 
which meet at that point. Now let us suppose 
that this observation is being made on the 
parenchyma of the corpus cavernosum, the 
arteries of which have been previously injected 
with fine injection. Where do we look for the 
injected arteries? Obviously in the septa, and 
especially at that thicker portion of the septum 
where several veins lie in contact. And what, 
we may ask, is the probable appearance of the 
arteries in that star-like point of septum which 
I have described above? I can answer this 
question, from repeated observation. It is 
that of a short trunk giving off two, three, or 
four small and short terminal branches, which 
diverge in an oblique direction from the ex- 
tremity of the small trunk, and terminate 
abruptly at the cut margin of the septum. I 
have seen the appearances here described many 
times, sometimes better, sometimes less dis- 
tinct, and more frequently as a bifid division 
than another, and these I apprehend are the 
arterie helicine of Miiller. Besides the pre- 
ceding, the special characters of the arterie 
helicine are their projection in the form of a 
tuft into a venous canal, and the curved, 
swollen, and conical form of the small branches 
