59 



ical colls oi" varying appearance. VHiile some (fig. 45) 

 are coarsely granular, others are almost homogenous. The 

 nuclei lie to one side of the cells. 



The other type of structure (figs. 50-52) I am con- 

 fident tliough not perfectly sure, is also derived from the 

 dendritic processes, along with a modification of the sur- 

 rovmding epitheliiom. The developed structure is of re- 

 markable ai^pearance (fig. 52). The base is composed of 

 modified epitheli-um cells of the v/all of the lamina. The 

 nuclei stain liglitly and lie in a granular protoplasm, 

 from which deeply staining rods project into the blood - 

 space, but from which they are separated by a membrane 

 formed of very flat cells. The development of this stinac- 

 tvu'e seems to be as f ollov/s : When the dendritic proces- 

 ses penetrate among the epithelial cells (fig. 49) , the 

 filaments are arranged lengthwise; soon they take on a 

 vertical position (fig. 50) enlarge, and become covered by 

 the cap-like membrane (figs. 50-52). If this derivation 

 be tho correct one, then the rods in fig. 52 have been 

 formed by the enlargement of the filaments of tlie dendri- 

 tic structures. In the lamina the rods project into the 

 blood-space; in the afferent branchial vein, away from the 



