EXPLANATION OF THE PLATES. 



The majority of these, I am now disposed to think, 

 are contained in the walls of the vessels constituting 

 the Malpighian plexus. The figure b is after Bow- 

 man, and shows the afferent artery and the efferent 

 vein of the Malpighian tuft, also the connection 

 of the tube with the Malpighian body itself; c, 

 loose epithelial cells of the tubes. 



Fig. 4. Tube of the testis, more highly magnified, displaying 

 the innumerable granular cells which fill the tube 

 as well as the structure of the tube itself. 



