FORMATION OF THE EP1DIDYMIS. 999 



ununited parts of the Miillerian ducts disappear, excepting, as suggested by Kobelt, 

 their upper extremities, which seem to be the source of the hydatids of Morgagni. 

 The excretory duct of the "Wolffian body, from the base of that body to its orifice, is 

 converted into vas deferens and ejaculatory duct, the vesicula seminalis being formed 

 as a diverticulum from its lower part. 



With respect to the formation of the epididymis, our information is not altogether 

 complete. According to the greater number of the most recent observations, it 

 appears certain that the larger convoluted seminal tube, which forms the body and 

 globus minor of the-epididyinis, arises by a change or adaptation of that part of the 

 Wolffian duct which runs along the outer side of the organ. The vas aberrans or vasa 

 aberrantia of Haller appear to be the remains also in a more highly convoluted form 

 of one or more of the tubes of the Wolffian body still adhering to the excretory duct 

 of the organ, and their communication with the main tube of the epididymis receives 

 an explanation from that circumstance. But there are no direct observations on 

 record of the process of conversion of these foetal structures into the permanent forms. 

 As to the coni vasculosi in the upper part of the epididymis, still more doubt has pre- 

 vailed. Since Mailer's discovery in birds of the collateral duct named after him, and 

 the extension of this discovery to mammals, it has been customary to regard the 

 upper part of the epididymis as produced by a transformation of the tubes and duct 

 in the upper part of the Wolffian body, according to the views most fully given by 

 Kobelt ; but doubts have been entertained by some as to the correctness of this view, 

 and more recent observations by Banks appear to prove that it must, in some degree, 

 be modified. 



According to Banks, the origin of the coni vasculod is due to a process of develop- 

 ment occurring in a new structure or mass of blastema which had been previously 

 observed by Cleland, and which is deposited at the upper end of the Wolffian body, 

 and close to the Mullerian duct. Within this blastema Cleland showed that the tubes 

 of the efferent seminal vessels and the coni vasculosi, together with the tube which 

 connects them, are formed anew, while the tubes of the adjacent part of the Wolffian 

 body are undergoing an atrophic degeneration. This has been confirmed by the de- 

 tailed observations of Banks, who has further shown the continuity of their uniting 

 tube with the Wolffian excretory duct. 



Should this view prove to be correct, the caput epididymis must be regarded not 

 simply as a conversion of the upper part of the Wolffian body, but rather as a new 

 formation or superinduced development in blastema connected with it. 



The coni vasculosi, so formed, become connected with the body of the testicle by 

 means of a short straight cord, which is afterwards subdivided into the vasa efferentia. 

 The peritoneal elevation descending from the testis towards the lower extremity of the 

 Wolffian body, is the upper part of the plica gubernatrix, and becomes shortened as 

 the testicle descends to meet the lower end of the epididymis ; the peritoneal elevation 

 which passes down into the scrotum, and is continuous with the other, is the more 

 important part of the plica gubernatrix, connected with the gubernaculum testis. 

 The spermatic artery is originally a branch of one of those which go to the 

 Wolffian body, and ascends from the surface of the Wolffian body to the upper part of 

 the testis, along the ligaments connecting them ; but, as the testis descends, the artery 

 lies entirely above it, and the secreting substance of the Wolffian body remains adherent to 

 it ; and hence it is that the organ of Giraldes, which consists of persistent Wolffian 

 tubules, is found in a position superior to the epididymis. (For a fuller account 

 of this complicated subject the student is referred to Banks " On the Wolffian 

 Bodies." Edin. 1864.) 



The descent of the testicles is a term applied to the passage of the testes from the 

 abdominal cavity into the scrotum. The testicle enters the internal inguinal ring in 

 the seventh month of foetal life : by the end of the eighth month it has descended 

 into the scrotum, and, a little time before birth, the narrow neck of the peritoneal 

 pouch, by which it previously communicated with the general peritoneal cavity, 

 becomes closed in the manner elsewhere described (p. 965), and the proeess of peri- 

 toneum, now entirely shut off from the abdominal cavity, remains as an independent 

 serous sac. The peritoneal pouch, or processus vaginalis, which passes down into the 

 scrotum, precedes the testis considerably in its descent, and into its posterior part 

 there projects a considerable columnar elevation already alluded to, which is filled 

 with soft tissue, and is termed plica ffubernafrix. There is likewise a fibrous struc- 



