STRUCTURE.] 



NUMBER OF STOMATES. 



145 



Memoir on the impregnation of Orchidea.} This idea is con- 

 firmed by the structure of Yucca (Plate III. fig. 10.), in 

 which the four oblong vesicles surrounding the stomate are 

 evidently of the same nature as the free spheroidal vesicles 

 (cytoblasts ?) contained in the cells of the cuticle. 



The following table of the proportion of stomates on the 

 surface of various organs will serve to give some idea of their 

 relative abundance. The first twenty-eight cases are taken 

 from Thomson's Treatise on Vegetable Physiology, in the 

 Library of Useful Knowledge. For the remainder I am 

 answerable : 



VOL. T. 



