THE STOMATA. 71 



mentioned them under the name of Cortical Pores (pori 

 corticales; pores corticaux). But as neither of these 

 compound names is strictly exact, and as a simple term 

 is more convenient, I prefer, now, to designate them by 

 the name of Stomata, which Link has given them. I 

 prefer it to that of Pores, which is employed in very 

 different senses, for designating every kind of little 

 orifice. 



The Stomata present themselves under the form of 

 oval pores, sometimes almost round, at others rather 

 elongated. Their size, which varies in different plants, 

 is commonly in accordance with the meshes marked on 

 the cuticle. Liliaceous plants, and in general those of 

 a loose tissue, have them commonly larger and fewer ; 

 those 'of a more compact tissue have them smaller, and 

 nearer one another. The open orifice of the stomata 

 has been seen and unanimously admitted by all ob- 

 servers, except Mirbel, who, after having admitted and 

 figured it in his first works, supposes (I know not what 

 foundation he has for so doing) that this orifice is an 

 optical illusion." One may especially observe the porosity 

 of the stomata in this, — that their orifice is equally seen, 

 whether the inferior or superior surface of the cuticle 

 be observed. Not only do all other anatomists admit 

 that the stomata are really perforated, but that the 

 openings vary in size according to circumstances : they 

 are, in general, open in leaves which grow well, and in 

 parts exposed to the sun ; they are less open, or some- 

 times entirely closed, on the surfaces of leaves which 

 are very old, or which have not been exposed to the 

 light for some time. Their border has the appearance 

 of a kind of oval sphincter, capable of being opened 

 and closed : the line which surrounds this sphincter is 

 alwavs continuous with those which form the network of 

 the cuticle : under this, and in the interval between the 



