Description of Plate 15. 



Peritoneal Epithelum of the Cat. 



Tigs. 7, 8, and 9. Three preparations from the mesentery. 

 These figures are of great interest because they 

 show how easily one might mistake the opening in 

 the first for a stomata and in the last two figures it 

 would be possible to say that they were small cells 

 filling up the opening of the stomata. Their posi- 

 tion corresponds to that assigned to stomata by 

 Klein, i. e., "in the center of radially arranged, rel- 

 atively large endothelial cells." 



Pig. 10. Prom the mesentery. Note especially the figure which 

 is shown more highly magnified at the left. As 

 viewed under a low power the point indicated ap- 

 pears as one of the so-called stigmata, but when 

 viewed under a higher amplification, especially if 

 an Abbe stereoscpic eye-piece is used, it is easily 

 seen that the dark spot is under the epithelial cells 

 and that the cell boundaries are intact. 



Pig. 11. Prom the mesentery. This figure shows the same ap- 

 pearance as figure 6, and also illustrates the effect 

 of stretching. 



Pigs. 1-10 from the Cat; fig. 11 from the Frog. All figures 

 were drawn under the camera lucida. 



