358 s. HATTA : 



A pair of the glomeruli (figs. 108 and 109,^/.). is seen adher- 

 ing on the median side of the tubule on each side and lined with 

 the visceral peritoneum. The glomerulus represented in the 

 last stage by a folding of the peritoneum which covers the tubules 

 from the third pair to the fourth^*, is reduced, at present, into a pair 

 of sacs of this membrane projecting on each side between the 

 fourth and the fifth tubules ; the other part of the folded membrane 

 becomes adhered firmly to the walls of either the tubules or the 

 body-cavity leaving no space of sacculation, — in short, a pair 

 of long fokls, extending from the anterior part of the third 

 tubule to the fiftli in the last stage, is reduced into a pair of sacs 

 found in the position just mentioned. The inside of the sacs 

 is compactly filled up with free-cells and communicates with 

 the aorta tract and with the space outside the pronephros, 

 where free-cells to be afterwards transformed into the anterior 

 cardinal vein have been observed already from the foregoing 

 stage. 



The section represented in fig. 110 fortunately passes sym- 

 metrically through a pair of the nephrostomes {nst.a) and of the 

 tubules ipt.a) hanging down in the peritoneal cavity. This is 

 the fifth or the hindmost pair of the i^ronephric tubules in the 

 present stage. The communication of the tubules with the collect- 

 ing duct is seen in the section behind this. The tubules present 

 also some antero-posterior bendings. Posterior to this, no tubule 

 is found. 



The pro7iephric tubules m the j^resent stage are, therefore, re- 

 duced into the miniinum number, i.e., three pa ir.s~\ all of 2ühieh are 

 retained so long as the organ functions as the excretory apparatus 



1) See p. 355. 



2) We occasionally find the fonr tubules to persist, and the additional tubule is the sixth. 



