PENIS. 



909 



just as well in one direction as in another. 

 Moreover, when the uterus has been subject to 

 irregular spasmodic contractions during the last 

 week or two of pregnancy, by which its form 

 is more or less altered, we frequently find that 

 when labour comes on the child presents with 

 the arm or shoulder. It is chiefly to this cause 

 that we must attribute those remarkable cases 

 which every now and then occur of the arm or 

 shoulder presenting in four or five successive 

 labours in the same individual, a fact winch 

 was first pointed out by Professor Naegele, sen. 

 The full-grown living foetus can, therefore, pre- 

 sent in only three ways, viz. with the head or 

 face, with the nates or inferior extremities, and 

 with the arm or shoulder. When other parts 

 of the child present, it arises either from its 

 having been some time dead in utero or from 

 being premature. 



(Edward Right/.) 



PELVIS. See SUPPLEMENT. 



PENIS. (Membrum virile; Grec. atfyew 

 euftow, Germ, das died, or die Rut/ie ; 

 Fran, verge; Ital. membra virile.) 



The term penis would appear from its deri- 

 vation (a pendendo) to have been the popular 

 designation of the male organ of man and of 

 the higher animals among the Roman people. 

 Like many other terms that we have received 

 from our predecessors, the present has reference 

 to a merely visual character of the organ in a 

 small group of animals, irrespective of the 

 important office which it is intended to fulfil in 

 the general animal economy. At the present 

 day, however, with a more enlarged scale of 

 information with regard to the laws and attributes 

 of living beings, while we retain the name, we 

 assign to it a more compiehensive definition than 

 its original application was intended to convey. 



The penis, throughout the animal kingdom, 

 is the organ of transmission of the male fluid 

 to the germinal product of the female sexual 

 apparatus; and in the mammiferous class it 

 performs the additional office of efferent duct 

 to the urinary secretion. In consideration of 

 its more obvious purpose, the penis has been 

 termed the organ of intromission; but this 

 appellation, though correct in general, is incor- 

 rect in particular instances, for there are many 

 among the inferior animals in which a rudi- 

 mentary penis exists, but no intromission can 

 possibly occur. 



As generation divides its claim with nutrition 

 in the lowest animal organisms, we are natu- 

 rally led to the expectation of finding the repre- 

 sentative of this organ among the lowest divisions 

 of the animal scale, and this expectation is 

 realized by research. In proceeding to this 

 investigation, however, it cannot too strongly 

 be impressed upon the mind, that in the lowest 

 even as in the highest, modifications do occur 

 which are conformable to the wants or conve- 

 nience of the animals in whom they are found, 

 without reference to any supposed gradation of 

 developement or improvement. Thus in Infu- 

 soria a sexual apparatus consisting of ovary, 

 testis, and vesicula? seminales, has been de- 



scribed by Ehrenberg; and in Rotiftra the 

 same author has observed a contractile organ 

 which serves to impel the seminal fluid into 

 the oviduct. Here, then, almost on the boun- 

 dary line of the animal world, is a self-impreg- 

 nating animal, provided with a distinct trans- 

 nnttent organ by which impregnation is effected. 

 But remarkable as this conformation may appear 

 at first sight, examples equally wonderful 

 become multiplied as we proceed onwards in 

 our enquiry. 



Bory St. Vincent has pointed out the existence 

 of an intromittent spiculum in the Vinegar Eel 

 (anguillula aceti), one of the Vibriomdae; and 

 Ehrenberg has observed a similar structure in 

 another species, the Anguillula fluviatilis. 

 Among the Cestoid Enluzoa, which are andro- 

 gynous, a distinct intromittent organ is found 

 in Ligula and Tenia solium. In Trematoda, 

 which are likewise androgynous, but impregnate 

 by mutual concurrence, a penis is also met 

 with, and is of considerable size. In Acantho- 

 cephala, the large intromittent organ of Echi- 

 norynchus gigas, the entozoon of the kidney, 

 has been described by Cloquet; and in Nema- 

 toidea the penis has attained a size and impor- 

 tance which renders it a generic character. 

 Thus the genus Filaria is distinguished from 

 Trichocephalus by a difference in form of the 

 preputial covering, and a similar character 

 distinguishes Ascaris from both the preceding. 

 Most of the smaller species of Ascaris are 

 remarkable, from possessing a double intro- 

 mittent organ, and a similar conformation is 

 met with in Linguatula, the entozoon of the 

 frontal sinuses of the canine race; in Cucul- 

 lanus, and in Syngamus trachealis, the tracheal 

 parasite of gallinaceous birds. 



Proceeding a step higher in the as.imal scale 

 we find in the class Annelida thai the organs 

 of generation are hermaphrodite, and so dis- 

 posed as to admit of mutual impregnation. 

 In some genera the penis is well developed 

 and distinct, as in Planaria and Hirudo; but 

 in others the mutual apposition of the sexes is 

 so perfect as to render an intromittent organ 

 unnecessary. On this principle the penis is 

 absent in the Earth-worm. In the Leech the 

 penis is long and slender, placed on the twenty- 

 fourth segment of the body, while the vulva 

 occupies the twenty-ninth. 



In Cirrhopoda, the barnacles or acorns of the 

 sea, the intromittent organ is well developed, 

 and from the mode of existence of these animals 

 and their hermaphrodite organization, may be 

 employed as a means of self or of reciprocal 

 impregnation. 



The class Crustacea is composed of animals 

 which are dioecious in their sexual organization, 

 and whose males are provided with a distinct 

 intromittent organ. In the lowest groups, 

 namely, the Entomostracous Lerneae, the penis 

 is double ; and in Decapoda and Brachiura it 

 is temporary and formed by an eversion of the 

 vas deferens, an adaptation of means to an end 

 that we shall find repeated among the lower 

 classes of Vertebrata. Throughout the whole 

 of this class impregnation is effected by reci- 

 procal union. 



