298 CONTRACTILE TISSUE. 



parts formed in one animal of the elastic yellow tissue, are in 

 others composed of muscular fibres. Thus, the suspensory 

 ligaments of the sheath of the penis, are ligamentous in the 

 horse, and muscular in the mule and bull. The middle coat of 

 the arteries, which is composed of the elastic yellow tissue in 

 man, is muscular in certain parts of the arterial system of the 

 elephant. 



— The kindred nature of these two tissues, is likewise strongly 

 manifested by chemical analysis. The yellow elastic tissue 

 consists chemically of albumen, osmazome and fibrine.* The 

 thick yellow elastic ligament which supports the weight of the 

 abdominal viscera in the horse, and others of the solipediae, 

 consists, in man, only of the fascia superficialis abdominis, and 

 forms, as a late writer is disposed to think, the abdominal pouch, 

 (poche musculaire,) of the didelphic animals, such as the 

 opossum and kangaroo. 



— The parietes of the urethra, which, in man, is strongly elastic, 

 in the horse and many other animals is endowed with a strong 

 coat of palish muscular fibres. On close examination it wiU 

 be found in man, that the reddish fibres of the contractile tissue 

 which constitute the dartos muscle, are also extended so as to 

 cover the corpus cavernosum penis and the urethra ; over this 

 latter organ it is not improbable that they sometimes become the 

 seat of stricture. They run more or less parallel, and near to 

 one another, over the scrotum, where they are interwoven with 

 transverse fibres and bundles of cellular substance — or they 

 form plexuses, as on the penis, which resemble the terminal 

 plexuses, of nerves, with this difference, that the individual 

 fibres interlace and amalgamate. 



— This same reddish contractile fibre is found by the microscope to 

 be interwoven in various places with the tissue of the skin, and 

 that peculiar corrugation of the skin known under the name of 

 goose flesh, is supposed to be produced by their agency. They 

 act with such force upon the scrotum, as occasionally to make 

 it hard as a ball, shrink it greatly in size, and force the testicles 



* Consid. sur les aponeuroses abdom. servant d'inlroduction a I'histoire des 

 Hernies, dans les Monodactyles, par Girard, fils. 



