74 



ON THE PLANT-CELL. 



flatter, and the intercellular passage itself formed of a larger or smaller 

 number of cells. In the Marchantia four cells are usually found ; in 



83 



8-1 



Cycas, and at the base of the leaves of Nelumbium (fig. 85.), a much 

 greater number. In most cases the epidermal cells lie on the same plane 

 with the others, but in Cycas and Marchantia they are elevated so as 

 to form a semicircular wart open at the point. In some instances a 

 kind of stunting takes place, which, in the leaves of Opuntice, is almost 

 normal. In this case, from three to five semi -lunar cells are pressed irre- 

 gularly one upon another. 



The contents of the stomatic cells, without exception, resemble those 

 of the adjacent parenchyma, seldom or never those of the epidermal cells 

 (figs. 83, 84.). I know of only a few cases, as Agave lurida, Aloe nigri- 



83 Perpendicular section of the surface of the leaf of Hakea amplexifolia. The 

 stomate forms a large cavity, the bottom of which is closed on every side by two cells, 

 which embrace between them the two special stomatic cells. The loose parenchyma 

 contains many oddly-formed cells. 



83 Epidermis from the under surface of the leaves of Tradescantia discolor. The 

 hatched cells contain a dark-red fluid. The two stomatic cells are surrounded by four 

 regular cells, with perfectly clear contents. 



84 A perpendicular section of the surface of the above, in the direction a- b. The 

 epidermal cells, filled with red sap, present a vacant space, which is closed externally by 

 the flat clear cells, and the stomatic cells filled with chlorophyll. 



