388 CHARLES H. SWIFT 



stroma. The basement membrane appears wavy bat is continu- 

 ous around the swelling. The buds enlarge and elongate but 

 remain attached to the germinal epithelium for some time (fig. 

 5, Swift, '15). These cords, which are at first small, are evi- 

 dently of germinal epithelium origin, for the basement mem- 

 brane of the latter structure is, for some time, continuous around 

 the cord. Neither are they formed by infolding or invagination 

 of the germinal epithelium, for in that case a tubular lumen 

 would be present in each cord, and in some cases could be 

 seen connected with the coelomic cavity. They are simply 

 the result of increased local mitotic activity in the germinal 

 epithelium. The primordial germ-cells which are present in the 

 cords do not play any evident role in their formation, for none 

 are ever found dividing just at the time of cord formation, 

 while the peritoneal cells show signs of increased activity. 



Although the cords begin to appear at 5| days, yet it is not 

 until 12 hours later that the greatest activity of the germinal 

 epithelium in their production occurs. At 6§ days they have 

 about ceased to appear. 



At the end of the period of cord production the interior of 

 the gonad seems to be made up nearly entirely of sexual cords. 

 They are close together, separated from one another by a little 

 stroma; a majority of the cords are no longer attached to the 

 germinal epithelium but are still surrounded by a definite base- 

 ment membrane. 



The cords have become autonomous, for, although no longer 

 attached to the germinal epithelium, they are growing rapidly as 

 is indicated by the rapid increase in diameter of the cord and 

 size of the gonads. 



The cords have a definite orientation — they are straight and 

 extend from the germinal epithelium down towards the Wolffian 

 body. 



The primordial germ-cells are during this period found in 

 three situations in the gonad, in the germinal epithelium, in the 

 sexual cord, and in the small amount of stroma between the 

 cords. 



