10-1 JESSE LE EOY CONEL 



pronephric tubules and they absorb much stain. The second 

 Malpighian body is interpreted as being the first Malpighian 

 body of the mesonephros. It is connected by a tubule to a short 

 piece of the segmental mesonephric duct which lies in the lumen 

 of the pronephric vein. The vein ends blindly with this piece of 

 the mesonephric duct a few sections posterior to the Malpighian 

 body. Furthermore, two pronephric tubules, which open into 

 the capsule of the Malpighian body of the pronephros, extend 

 into the pronephric vein, unite and enter the piece of mesonephric 

 duct. Surrounding the base of these tubules, just before they 

 enter the mesonephric duct, is a small amount of the central 

 mass. This short piece of duct contains waste particles through- 

 out its entire extent. The continuous duct of the mesonephros, 

 in this specimen, begins 5 mm. posterior to this short piece and 

 there is no connection whatever between them. When there is 

 but one Malpighian body it usually ends blindly, although the 

 capsule may be drawn out posteriorly into the very small duct 

 which ends in the connective tissue. 



In shape the Malpighian body of the pronephros of both 

 Bdellostoma and Myxine is usually an elongated oval, although 

 it may be almost round or flattened somewhat laterally. In 

 Myxine one end is, as a rule, more pointed than the other. 



The glomerulus of the Malpighian body in Bdellostoma is 

 comparatively compact and uniform in structure. The surface 

 is smooth but shghtly convoluted, and is covered by the epithelial 

 lining of Bowman's capsule. There are lines of division which 

 separate the glomerulus here and there into lobes (fig. 40), and 

 in almost every specimen are one or more small cavities, inside 

 of which are blood corpuscles or blood plasma. 



In appearance the glomerulus of the youngest Myxine (no. 

 18) is very similar to that of Bdellostoma. In the older speci- 

 mens, however, the lobed condition is more apparent, it is much 

 less compact and has a more or less shriveled appearance, and 

 the spaces in the glomerular mass are more numerous and larger. 

 Webs and strands of connective tissue appear everywhere in the 

 glomerulus and around the outside of the lining of Bowman's 

 capsule. In the oldest Myxine (no. 10) these changes are most 





