THE STOMATA OF PLANTS. 



63 



in water, or grow in darkness, and also the lowest classes of plants, as mushrooms, sea- 

 weeds, and lichens, except mosses. Neither are they found upon all parts of any plant, 

 but are absent from the roots and ribs of leaves. They are most abundantly found on 



Fit,'. 110. Fig. ill. 



Fig. 110. A side view of the modified stomata of the NKRIUM OI.TSANDER, and of a BANKSIA, in 

 which they are seen clustered together at the bottom of a pit, a, the entrance of which is defended 

 by hairs, b. 



Fig. 111. A front view of the same organ. 



the under surface of such leaves as present one surface to the soil (Fig. 106), hut on both 

 surfaces equally, if the edges only be directed vertically. They are also met with on 

 the cuticle of stems, on flowers, and even on the seeds of a few plants, and on their 

 cotyledons. 



The number of stomata found upon a moderate-sized leaf is sometimes prodigious, 

 amounting in some instances to 160,000 on each square inch of surface. Thomson 

 gives the following enumeration, which shows not only the total number but the 

 relative quantity on the two surfaces of the leaf: 



On each square inch 

 of upper side, and of under sicJe. 



12,000 



none. 



38,500 



Alisma Plantago (Water plantain) ..... 



Coboea scandens 



Dianthus Caryophyllus (Pink) 



Daphne Mezcreum (Mezercum) none. 



Jlypericum Grandiflorum (St. John's Wort) . . . none. 



Ilex (Holly) none. 



Iris Germaniea (Iris) 11,572 



Olea Europoea (Olive) none. 



Pseonia (Pseony) none. 



Pvrus (Pear) none. 



"Rurnex Acetosa (common Sorrel) 11,088 



Tussilago Farfara (Coltsfoot) 1,200 



Vitis vinifera (Vine) none. 



Viscum album (Mistletoe) 200 



Syringa vulgaris none. 



6,000 

 20,000 

 38,500 

 4,000 

 47,800 

 63,600 

 11,572 

 57,600 

 13,790 

 24,000 

 2*0,000 

 12,500 

 13,600 

 200 

 160,000 



Of 28 plants in this table which had been examined, 15, or more than- half, had no 



