STOMATES 



271 



in water on a slide. Make sketches of the different kinds 



of hairs. 



437. STOMATES. Stomates or breathing-pores are 



small openings or pores in the epidermis 



of leaves and soft stems to allow the 



passage of air and other gases and vapors. 



They are placed near the large intercel- 

 lular spaces of the mesophyll. Fig. 413 



shows the usual structure. There are two raninm leaf.show- 



guard cells at the mouth of each stomate, 



which may in most cases open 

 or close the passage as the condi- 

 tions of the atmosphere may re- 

 quire. In Pig. 414 is shown a 

 '^^fi case in which then- are compound 



guard cells, thai of ivy. < >n the 

 111 s tvy. showing mar gins of certain leaves, as of 



compound guard cells. 



fuchsia, impatiens, cabbage, are 

 modified stomates known as water-pores. 



138. Stomates are very numerous, as will be seen from 

 the numbers giving the pores to each square inch of leaf 

 surface : 



I tower surface i pi r 



Peony 13,790 



Bolly 63,600 



Lilac 160,000 



Mistletoe 200 200 



TradeBcantia 2,1 2, > 



Garden Flag 11,572 1 1,572 



The arrangemenl of Btomates on the leaf differs with 

 each kind of plant. Pigs. 415 and 116 show Btomates on 

 two plant-, and also the outlines of contiguous epidermal 

 cells. The guard cells contain chlorophyll. 



139. fall of Tin- LEAF. In nm-i common deciduous 

 plant-, when the season's work for the leaf is ended, the 

 nutritious matter is withdrawn into the stem, and a layer 



