ERECTILE TISSUE. 



145 



small, pale, soft, and shrunken; but when 

 excited to erection, they become increased in 

 size, stiff, red, and distended with blood, at 

 the same time that their sensibility i remark- 

 ably exalted. The foregoing remarks apply 

 equally to the cutaneous papillae, particularly 

 those on the pulpy extremities of the ringers, 

 where the sense of touch is developed in its 

 highest degree of perfection. 



Erectile tissue has also been recognised in 

 the callosities on the buttocks of some of the 

 quadrumana, in the comb and gills of the 

 cock, the wattles of the turkey, and in the 

 tongue of the chamelion.* It is not improbable 

 that this tissue enters into the structure of the 

 iris ; and Beclard seems disposed to consider 

 that it exists in the spleen, as well from the 

 appearance which that organ presents when a 

 section of it is made, as from the different 

 states in which it is found on opening the 

 bodies of animals ; being sometimes contracted 

 and corrugated on the surface, and at other 

 times plump, smooth, and swollen. 



In some of the situations above enumerated, 

 the erectile tissue is enclosed in a fibrous sheath 

 which limits its extent and determines the form 

 of the organs in which it occurs ; while in other 

 situations it is deployed superficially, as in the 

 tegumentary organs. 



It is in the corpora cavernosa penis and 

 corpus spongiosum urethras, however, that the 

 erectile tissue has been more especially made 

 the subject of anatomical and physiological 

 research ; and the results of the investigations 

 instituted in these organs have been rather 

 inferred from analogy than directly proved as 

 equally applicable to it in- all other situations 

 in which its existence has been indicated. 



According to De Graaf, Ruysch, Duverney, 

 Boerhaave, Haller, and Bichat, the cavernous 

 bodies of the penis and urethra consist of a 

 loose and elastic spongy tissue formed of in- 

 numerable cells, into which, during erection, 

 blood is poured from the arteries, and from 

 which it is afterwards removed by an absorbing 

 power of the veins. Such an opinion would 

 accord with the appearances observed by 

 examining sections of this structure after having 

 been inflated and dried, but careful examina- 

 tion of it when previously prepared by injec- 

 tion, proves the foregoing opinion to be founded 

 in error. 



Vesalius, who appears to have directed his 

 attention to the particular nature of this struc- 

 ture in the penis, describes it as composed of 

 innumerable fasciculi of arteries and veins 

 closely interwoven, and included in an invest- 

 ing sheath. 



Malpighi considered it as com posed of diver- 

 ticula or appendices of veins. 



Mascagni, who at one time believed in the 

 existence of cells interposed between the veins 

 and arteries, in consequence of subsequent 

 researches abandoned that opinion, and de- 

 monstrated the fact, that a plexus of veins with 

 arteries corresponding, but smaller ind less 



* On the structure and mechanism of the tongue 

 of the chamelion, by J. Houston, in Transactions 

 of the Royal Irish Academy, vol. xv. 

 VOL. II. 



numerous, formed the corpus spongiosum 

 urethra, glans, and plexus retiformis, and that 

 the arteries entering this substance terminated 

 in the commencement of veins. 



Mr. Hunter remarked that the corpus spon- 

 giosum urethrae and glans penis were not 

 spongy or cellular, but made up of a plexus of 

 veins, and that this structure is discernible in 

 the human subject, but much more distinctly 

 seen in many animals, as the horse. &c. 



Subsequent researches respecting the struc- 

 ture of the penis and clitoris of man, the horse, 

 elephant, ram, &c. have been instituted by 

 Duverney, Mascagni, Baron Cuvier, Tiede- 

 mann, Ribes, Moreschi, Panizza, Beclard, 

 Weber, &c. and the result has been a con- 

 firmation of the views developed by Vesalius, 

 Malpighi, and Hunter. 



Moreschi, in particular, has shewn that the 

 corpora cavernosa penis, corpus spongiosum 

 urethrae, and glans consist of a congeries of fine 

 vessels in all animals, whether covered by skin, 

 hairs, spines, or scales ; and that these vessels, 

 which are principally veins, are characterized 

 by their abundance, tenuity, and softness, 

 which distinguish them from the veins in the 

 muscles and other parts of the body. 



The annexed figure (jig. 97) from Moreschi 



Fig. 97. 



