ii SENSIBILITY OF THE INTERNAL ORGANS 81 



in animals, although in different degrees, inasmuch as they are 

 subordinated to the higher development of the intellect and the 

 evolution of the aesthetic and moral sense. 



One further physiological problem must here be taken into 

 consideration. Is the sense of pleasure, which is localised especi- 

 ally in the mucous membrane of the internal genital organs of 

 both sexes, a special modification of the sense of contact, or is it 

 a special sense, served by specific corpuscles or nerve -endings ? 



Much morphological research has been directed to this subject, 

 but no conclusive solution has at present been reached. 



Krause (1866-81) first studied the nerve-endings in the external 

 genital organs of both sexes, and described special corpuscles in 

 the form of end-bulbs, which he termed " genital corpuscles." Of 

 the many other histologists who have studied this subject, Retzius 

 (1876-90), Aronson (1886), Dogiel (1893), Timofeew (1891), and 

 Sfameni (1904) deserve special mention. 



Retzius and Aronson, who investigated the skin of the glans 

 penis, clitoris, and vagina of the rabbit, discovered large and small 

 genital corpuscles. They found that the nerve -fibres to these 

 parts divided into fine branches, which ended in knobs. 



Dogiel investigated the human genitals as well as those of 

 animals. In addition to Krause's end-bulbs or spherical corpuscles, 

 large and small, he also found Meissner's corpuscles. He further 

 discovered that filaments ran out from Meissner's corpuscles, and 

 terminated in oval cuneiform or pyriform swellings, in the midst 

 of the cells of the deep layers of the epithelium ; by these con- 

 tinuity is established between 'the nerve corpuscles and the 

 epithelial cells. He, moreover, found a nerve network in the 

 epithelium which also reached the more superficial layers, in the 

 formation of which not only the myelinated fibres, but also the 

 fibres non-myelinated from their origin, participated. Timofeew 

 described a special capsulated nerve -ending in the male sexual 

 organs of certain mammals. Two distinct kinds of nerve-fibres 

 penetrate these one thick and medullated, which lose their 

 myelin sheath as soon as they emerge from the capsular sheath, 

 and then expand into the form of a band with dentellated edges, 

 and terminate at the opposite pole of the ramified or simple, 

 pointed or rounded corpuscle ; the other, much finer, which 

 also lose their myelin sheaths, and terminate after branching 

 repeatedly in delicate varicose fibrils which form a network. 

 He confirmed the presence of Pacinian corpuscles on the external, 

 genital organs of both sexes, as already described by Schweiger- 

 Seidel, Klein, Rauber, and others. 



Sfameni's more recent observations were made upon the genital 

 organs of the cow, sheep, mare, ass, bitch, and woman. In all 

 these species the differences in the nerve-endings are insignificant. 

 In any one animal the different types of corpuscles present an 



VOL. IV G 



