PENIS. 



911 



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 a state 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 

 to 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 penis is 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 Chimpanzee and 

 Orang, even this character of inferior organisa- 



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 Chimpanzee. 

 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 giant, 

 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 integument 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 



* Froriep's Notizen, No. 883. 



