ox SUPRAKENAL BODIES IX THE MOUSE. 233 



the anterior parts, bv an intervening tliiu septum of connective tissue 

 cells. Tliis septum, consisting of the two or three rows of cells, 

 runs from the peritoneal epitheHum in dorsal direction, and finally 

 separates itself into two branches, tlie one bending laterally and 

 covering the generati\e (jrgan, the other bending medially and cover- 

 ing the dorsal end of the suprarenal. 



The cells of tlie peritoneal epithelium which touches the supra- 

 renal blastema are arranged in a single row (fig. 6). But as we 

 proceed anteriorly (fig. 5) the epithelium cells are evidently 

 proliferating 5 they are actually pushed upwards and are even con- 

 tinuous with the suprarenal blastema. Tracing sections still anterior- 

 ly, the connection becomes more intimate, till near the anterior end 

 of the suprarenal (TL XXX. fig. 4) the |)eritonea] epithelium cannot be 

 distinguished from the suprarenal blastema itself. Here the septum 

 no longer exists between the suprarenal and generative organs. The 

 cells of the two blastema are laterally continuous with each other, the 

 two being indicated only Ijy the two rounded eminences projected 

 dorsal ward; ventrally they are both seen to be the proliferation of 

 the peritoneal epithelium. 



In a stage somewhat earlier than that above described, the sup- 

 rarenal blastema is not yet so distinct. Figs. 1-3 were taken from an 

 endjiyo in the later stage of the 11th day of gestation. Fig. 2 taken 

 frcjin near the anterior end of the left suprarenal blastema corresponds 

 with fig. 4, and figs. 1 and 3 taken on both sides at the middle 

 ot the organs corres[)ond with fig. 5. From the somewhat 

 detailed description of the previous stage, any further remarks will 

 not be needed. Only it may be added that the proliferating cells are 

 xevy indistinctly bounded dorsally, but a carefid study shows that 

 they are proliferated from the e[)itheliuni. Why I do not consider 

 these ])roliferatinL!; cells as the sole bei^'inniiiL;- of the u'enerative oru'an 



