REPRODUCTIVE SYSTEM OF FREE-MARTINS 469 



reproductive organs, much more than do normal embrj^os which 

 vary even more in size. 



For comparison the normal cf and 9 of the same size will first 

 be described. 



a. Conditions in the normal 



The males sectioned for comparative study are N21, measur- 

 ing 20 cm. and T4, the twin of free-martin 4, which measures 

 24 cm. The testis of the 20 cm. male, which had not yet be- 

 gun its descent, is 4.042 mm. long. The left testis of the 24 

 cm. d^ measures 8.67 mm. and had begun its descent into the 

 saccus vaginalis. The right testis in the same specimen had 

 almost reached the distal end of the scrotal sac. Otherwise, the 

 testes of these two specimens are approximately the same. Their 

 condition is shown in figures 9 and 10. The seminiferous tubules 

 are still solid cords, longer and more branched than in testes of 

 younger animals. They contain germ cells, some of which are 

 as yet in the indifferent stage, while others are in the growth 

 stages described by Schoenfeld.' In the 20 cm. cf one finds 

 primary spermatocytes in stages a to e. In the 24 cm. specimen 

 they are in stages a, e and f. In neither case were any mitoses 

 found. The spaces between the sex cords are filled with a large 

 amount of interstitial material made up chiefly of typical em- 

 bryonic connective tissue, but some of the cells have a wider 

 layer of cytoplasm around the nucleus and are polyhedral in 

 shape. These are young interstitial cells. The interstitial 

 space is wider in T4, the interstitial cells more numerous. The 

 characteristic male albuginea, consisting of layers of connective 

 tissue pressed compactly together, lies just beneath the superficial 

 peritoneum, surrounding the sex cord region. Blood vessels lie 

 in the inner deeper layer (tunica vasculosa). The rete cords can 

 be seen connected with the seminiferous tubules, but distinguished 

 from the latter by their luminal (fig. 10). 



The Wolffian body lateral to the gonad is almost completely 

 degenerated. From the anterior part of the Wolffian body is 

 formed the epididymis, much larger in these males than it was 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 23, XO. 2 , 



