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CHARLES H. SWIFT 



lumen is formed, not as one would suppose, by a fissure appear- 

 ing between cells and then enlarging, but by a liquefaction of 

 the cells in the central axis of the cord. When this destruction 

 which involves chiefly the peritoneal cells, is complete, a slit 

 appears in the debris and the lumen is formed (fig. 5). The peri- 



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Fig. 5 Portion of a transverse section through the right testis of a 20 day- 

 chick embryo. This section shows a seminiferous cord in which a lumen is be- 

 ginning to develop. The spermatogonia are next to the basement membrane, 

 with elongating peritoneal cells between them. Notice that the mitochondrial 

 crescents of the spermatogonia are next to the basement membrane of the cord. 

 A small mass of interstitial cells is present in the stroma. 



toneal cells are the principal sufferers because the spermato- 

 gonia have placed themselves along the wall. 

 ..:J do not know positively through what agency they are 

 .Enabled to place themselves against the basement membrane, 

 • byt suppose that it is through their ability to mo\'e like an 



