THE TESTICLES. 95 



vocal character, J. F. Meckel has very ingeniously suggested 

 that it forms the transition from cellular to muscular tissue, and 

 that there exists between it and other muscles the same relation 

 that there is between the muscles of the superior and of the in- 

 ferior orders of animals. Among the latter, the fibrous struc- 

 ture is indistinctly marked, and is masked by gelatine; an ele- 

 ment of the cellular tissue which envelops and conceals the 

 fibrine, an element of the muscular tissue. 



The fibres of the cremaster muscle, which are next in order, 

 form a very imperfect covering to the testicle, and belong rather 

 to the spermatic chord: what remains to be said concerning 

 them will be more properly introduced into the account of the 

 latter. The cellular substance that connects thedartos and the 

 cremaster with the tunica vaginalis forms a compact and perfect 

 lamina, sometimes spoken of as the Tunica Vaginalis Communis 

 Testis. There is one for each testicle, which it surrounds en- 

 tirely, as well as its chord, and connects the chord to the mar- 

 gin of the external abdominal ring, as stated in its account. 

 At its upper end it is continuous with the cellular substance that 

 unites the peritoneum to the parietes of the abdomen, as may 

 be proved by inflating it, when the air will penetrate accord- 

 ingly through the abdominal canal. 



The Peritestis, or Tunica Vaginalis, was originally a process of 

 peritoneum, communicating with the cavity of the latter through 

 the abdominal canal; but in the adult, it appears as a complete 

 and distinct sac. As it is very rigidly comparable to a double 

 night-cap drawn over the head, we accordingly find that the 

 testicle, along with the epididymis is pushed into it from behind. 

 That portion of the tunica vaginalis which is in contact with the 

 testicle, or rather with the tunica albuginea, adheres so closely 

 that it cannot be separated, except very partially and in shreds; 

 but it may be detached easily from the epididymis, with the con- 

 volutions of which it is in immediate contact. This sac is longer 

 and larger than the testicle itself, from which cause it ascends 

 for several lines above the superior end of the gland, and the 

 free part hangs loosely about it. Its cavity may, with but little 

 force, be injected so as to hold an ounce or two of fluid. 



This membrane is smooth and polished on the surface forming 



