138 STOMATES THEIR NATURE. [BOOK i, 



matter (Oryanogr. i. 80.) ; and recently Adolphe Brongniart, 

 in his beautiful figures of the anatomy of leaves, would seem 

 to have settled the question beyond all dispute. (Annales 

 des Sciences, vol. xxi.) Nevertheless there are anatomists of 

 high reputation who entertain a directly opposite opinion ; 

 denying the existence of passages, and considering the sto- 

 mates rather in the light of glands. Nees von Esenbeck and 

 Link have denied the existence of any perforation in the 

 stomates, and considered that the supposed opening is a space 

 more pellucid than the surrounding tissue, and that what 

 seems a closed up slit is the thickened border of the space. 

 Link further added in his Elementa (ed. 1. p. 225.), that the 

 obscuration of the centre of the stomates is caused by a pecu- 

 liar secretion of matter, as is plainly visible in Baryosma 

 serratum. To the views of these writers is to be added the 

 testimony of Brown (Suppl. prim. Prodr. p. 1.), who describes 

 the stomates as glands which are really almost always imper- 

 forate, with a disc formed by a membrane of greater or less 

 opaqueness, and even occasionally coloured; at the same 

 time he speaks of the disc being, perhaps, sometimes perfo- 

 rated. Link, however, has now abandoned his first idea 

 (Elementa, ed. 2, vol. ii. p. 6.), recognising them as openings; 

 most anatomists have come to the same conclusion, and 

 no reasonable doubt can now be entertained that the glandular 

 theory of Brown and others was founded on misconception. 



In no plants are stomates larger than in some Monocotyle- 

 dons ; they are, therefore, the best subjects for examination 

 for general purposes. In Crinum amabile they evidently 

 consist of two kidney-shaped cells filled with green matter, 

 lying in an area of the epidermis smaller than those that 

 surround it, and having their incurved sides next each other. 

 In some, at the part where the kidney- shaped cells come in 

 contact, there is an elevated ridge, dark, as if filled with air, 

 and having its principal diameter distinctly divided by a line. 

 (Plate III. fig. 11.) In this state the stomate is at rest : but 

 in others the kidney- shaped cells are much more curved ; 

 their sides are more separated from each other ; and there is 

 no elevated ridge : at their former line of contact there is an 

 opening so distinct and wide as to be equal to half the 

 diameter of one of the kidney-shaped cells. 



