514 MR. T. II. BURLEND ON THE UROGENITAL [Mar. 1, 



each is a swollen glandular .structure which secretes a tallowy 

 fluid of uncertain function. 



(b) Testes, vasa efferentia, sperm-ducts, and glands of Leydig. — 

 The bean-shaped testes attain a length of from 1^ to 2 inches 

 in the well-developed male adult, and are suspended from the 

 dorsal body- wall by peritoneum in the anterior region of the 

 abdominal cavity. The peritoneum also covers the ventral surface 

 of the corresponding Leydig's gland and sperm-duct, but not their 

 dorsal surfaces, whereas it closely invests each testis and then 

 passes over the neighbouring body-wall. In the centre of the 

 dorsal surface of the testis there is a crescent-shaped flap of 

 lymphoid tissue, between which and the inner border of the 

 testis the peritoneum is not contiguous, and so a space is left 

 between the latter and the testis (text-iig. 41, t.j\). 



The ventral surface of the gonad in the fresh condition presents 

 a white cortical and a greenish medullary area ; beneath the 

 peritoneum of the latter a network of minute vessels may be 

 detected by the aid of a lens (text-fig. 40, v.ef.t.). These are 

 continuous with the testis crypts and are filled with spermatozoa. 

 They unite to form larger vessels, the whole network — rete testis 

 — ultimately giving rise to six vasa efferentia, which are directed 

 towards the anteriorly coiled sperm-duct on the inner side of the 

 testis. After traversing, on the dorsal side of the peritoneum, 

 the space between the gonad and its duct, they pass into a. longi- 

 tudinal collecting duct, the most posterior of the vasa efferentia, 

 however, being an exception, since it never reaches the above- 

 mentioned duct but ends blindly in the peritoneum. 



The collector passes forwards and gradually sinks in between 

 the numerous coils of the sperm-duct of this region, but then 

 bifurcates, and the two ducts formed proceed some short distance 

 before finally fusing to establish the Leydig's duct or sperm-duct 

 by an increase in diameter, but in the nature of the lining 

 epithelium and contents identical with the collecting duct. 



The sperm-duct does not pass directly backwards but forms a 

 conspicuous much coiled structure which more posteriorly becomes 

 less intricate, so that its winding course may be followed. After 

 this, the diameter of the duct greatly increases and gives rise to a 

 long straight sperm-vesicle, which becomes constricted about one- 

 third of the distance from its posterior end, but enlarges again 

 and ultimately opens near the opening of its fellow on the other 

 side into a much narrower median urogenital sinus (text-fig. 41, 

 ur.s.). 



Running along the inner border of each sperm-duct, and later 

 becoming dorsal to the sperm-vesicles, are two white glands 

 showing distinct traces of metamerism, complete anteriorly but 

 not so marked at their posterior ends : these are the glands 

 of Leydig, almost ribbon-like in front, but less flattened dorso- 

 ventrally, and much wider behind. They extend from the level 

 of the middle of the testes to the constricted regions of the 

 sperm-vesicles. 



From each segment of Leydig's gland in front, there passes off 



