PENIS. 
soft parts and acts as an obstacle to intromis- 
sion, the penis is remarkable for its size and 
length. 
Among Birds, the penis is rudimentary in a 
great proportion of the class. In aquatic birds, 
however, it is large and constructed on the 
same principle as the penis of serpents, so as to 
be capable of eversion. In the order Anseres, 
the intromittent organ is remarkable for its 
length, and is furnished with a groove which 
runs spirally around its axis. In terrestrial 
birds, the penis is large and grooved, and pro- 
vided with a ligament of elastic tissue, which 
effects its retraction. 
Throughout the whole class of Mammifera, 
the existence of an intromittent organ, furnished 
with an urethral canal, is a common character. 
In Monotremata, the penis is not conspicuous 
externally, but is contained in a sheath distinct 
from the cloaca, and protrudes through the 
latter under the influence of excitation. In 
this order, moreover, we meet with the inte- 
resting condition of an urethral canal, which is 
intended solely for the purpose of transmitting 
the seminal secretion, while the urine passes 
away by the cloaca. In Marsupiata, the penis, 
which is of large size, is also situated in the in- 
terior of the animal in a sheath contiguous to 
the cloaca, but it passes through the latter when 
in astate of erection. Among Rodentia, the most 
remarkable character of the intromittent organ 
is the presence of recurved spines upon the glans 
penis ; this apparatus reminds us of the clasp- 
ing organs seen in insects and in the higher 
cartilaginous fishes, and is obviously intended 
te fulfil a similar function. The order Edentata 
affords two opposite conditions of the intro- 
mittent organ in relation to. size; these condi- 
tions having reference, as in Chelonia, to the 
convenience of the animals. Thus in the Bra- 
dypus or Sloth, the penis is rudimentary, while 
in the Armadillo the organ is exceedingly large. 
In Cetacea, which from the nature of the me- 
dium in which they live, are subject to impedi- 
ment in the impregnating act, the penisis enor- 
mous. In Ruminantia and Pachydermata the 
organ is of large size, and presents but little 
variety of form. In some genera it is more or 
less curved, while in the state of repose; in 
others it is straight. The intromittent organ in 
Carnivora is rendered remarkable by the pre- 
sence of a bone, the os penis, which is more or 
less developed in different genera. Thus in 
Plantigrade Carnivora it is of large size, while 
in the feline race it is cartilaginous and rudi- 
mentary. 
In all the orders of Mammifera hitherto ex- 
amined, the penis is contained either within a 
sheath in the interior of the body, as occurs in 
Monotremata, Marsupiata, and Cetacea, or in 
_ a sheath of the integument upon the exterior. 
But in Quadrumana, the transition class to 
man, the sheath of integument no longer exists, 
and the organ hangs pendent from its attach- 
ment. The os penis still remains to identify 
the quadrumanous race with the inferior classes, 
but in the higher genera, the Chimpanzée and 
_ Orang, even this character of inferior organisa- 
911 
tion is lost. Mayer," it is true, has declared 
the existence of a small cartilage, of a prismoid 
form, and about a line or a line and a half in 
length, in man. This he regards as the homologue 
of the os penis in inferior animals. It is 
situated, he says, in the submucous tissue of 
the upper part of the urethra within the glans 
penis ; but he finds it only in strong and pow- 
erful men. Should this observation be con- 
firmed by succeeding research, we ought to be 
able to find such a structure, even more consi- 
derable in its development, in the Chimpanzée. 
For my own part, 1 am unable to corroborate 
Mayer’s discovery, having failed in numerous 
examinations of the human organ instituted for 
the purpose of finding it. 
Having thus briefly reviewed the animal 
kingdom in relation to the existence of an 
organ of transmission for the reproductive secre- 
tion of the male, and having determined the 
conditions under which that organ is developed 
and its modifications produced, we may in the 
next place proceed to consider the conformation 
and structure of the penis, taking as the proper 
standard of comparison the intromittent organ 
of man, 
The penis of man is situated at the lower 
part of the abdomen, below and in front of the 
symphysis pubis, and presents some difference 
in character, accordant with its state of excite- 
ment or repose. In the latter condition it is 
cylindrical in form and hangs loosely in front 
of the scrotum; in the former, its shape is 
prismoid, with rounded edges and slightly 
grooved along the sides, one facet of the prism 
broader than the other two forming the upper 
surface or dorsum of the organ, and a rounded 
angle the inferior border. Moreover, in the 
state of repose, the organ makes a sudden curve 
in front of the pubis, the concavity of the bend 
looking downwards; while in the state of erec- 
tion it is directed upwards, and forms a gentle 
curve towards the parietes of the abdomen. 
For convenience of description and refer- 
ence, we are wont to consider the penis as 
divisible into a middle portion or body; the 
upper surface of the body being called the 
dorsum, a free and rounded extremity the glans, 
and a root or attached extremity by which it is 
connected with the ramus of the ischium at 
each side. The length and bulk of the organ 
vary with the conditions of erection and repose, 
and also with the individual. 
The anatomical constituents of the penis 
are, the integument and subcutaneous areolar 
tissue, with the fascia penis ; two bodies proper 
to this organ, the corpus cavernosum and cor- 
pus spongiosum, mucous membrane, muscles, 
vessels, and nerves. 
The tntegument of the penis is remarkable 
for the thinness and fineness of its texture, its 
exceeding elasticity, and generally for a deeper 
tint of colour than that of the surrounding skin. 
The tenuity of the skin is equal to that of the 
eyelids, but is exceeded by the integument of 
the scrotum, and contrasts very strongly with 
sg Froriep’s Notizen, No. 883, 
