44 



ORGANOGRAPHY. 



Fig. 94. 



^V T-\--..- 





/A ^ 



Fig. 94. Eijidennis of the leaf of a species of Saxifrage, showing clustered 



stomata, «. with intervening spates, e, e, in which they are absent. 



Fig. 95. Vertical section of the leaf of Oleander, c. Cavity filled with 

 hairs, with stomata at their sides, p. Parenchyma, e. Epidermis. 



The number of stomata also varies considerably. The fol- 

 lowing Table will give some idea of their abundance in the 

 leaves. 



Stomata in one square inch of surface. 



Stomata are not found upon all plants. Thus they are 

 absent from the lower orders of Flowerless Plants, as the Algaj, 

 Fungi, and Lichens. In the higher orders of such plants 

 they abound, as in Ferns and their allies, while in Liver- 

 wort* and Mosses they appear to be confined to certain organs. 

 They exist more or loss upon all Flowering Plants and their 

 organs. They arc, however, far more abundant upon those 

 which are grocn, thus occiirriiig especially u])on leaves as we 

 have seen, and particularly on the under surface of those organs 

 (see Table). On floating leaves, however, wc find thcra only 



