392 CHARLES H. SWIFT 



layer under the epithelium has thickened. In fact most of the 

 increase in the size of the testes is due to the increase in amount 

 of connective tissue. The cells of this tissue are still mesen- 

 chymal in character; cell boundaries are hard to determine and 

 the cytoplasmic processes of the cells unite forming a kind of 

 syncytium. The nuclei are round or oval (fig. 1). 



The seminiferous cords no longer run in a regular way as 

 described above, but form a kind of network. On studying 

 them one receives the impression that they have grown consid- 

 erably in length and as a result have had to become convo- 

 luted in order to adapt themselves to a slower growing space. 

 In all four embryos studied several peculiarities were found to 

 be common in regard to the seminiferous cords. In the first 

 place a cord runs only a short distance across the field before 

 being lost. This indicates folding (fig. 1). In the second 

 place there are more cords present in that part of the testis 

 next the Wolffian body, and here the net formed by the cords 

 is more compact. In the region towards the germinal epithe- 

 lium there is always a single cord which tends to run parallel 

 to the germinal epithelium separated from it by the developing 

 albuginea and from the other cords by a thick layer of stroma. 



The seminiferous cords are surrounded by a definite basement 

 membrane (fig. 1), which they acquired when given off from the 

 germinal epithelium. 



The cells present in the cords are principally of the perito- 

 neal t3^pe, although an occasional primordial germ-cell can be 

 seen (fig. 1). The cell walls of the peritoneal cells can be seen 

 but are not so distinct as formerly. Peritoneal cells are occa- 

 sionally seen dividing but the primordial germ-cells are still 

 quiescent. In this stage the increase in the cords is one of 

 length but not of diameter. 



In the 13 day embryo several important changes must be 

 recorded. 



There has been a great increase in the amount of stroma (fig. 

 2) and as a result of this, in the size of the testis, which is now 

 almost separated from the mesonephros. In an embryo four 

 days younger the stroma was present simply as a thin film be- 



