THE STOMATA. 75 



colour, have no stotnata either on their stems, or on the 

 imperfect rudiments of their scale-like leaves ; such as 

 Orohanche, Lathrma, Monotropa, Cuscuta, &c. ; on the 

 contrary, those which are green, as the Misseltoe (Fwcms), 

 and Loranthus, are abundantly supplied with them. 



The use of the stomata is an important point in 

 vegetable physiology and anatomy, and naturalists have 

 formed different opinions with regard to it. Perhaps 

 these organs can, imder different circumstances, perform 

 different offices. Some have attributed to them the 

 office of exuding the resinous or waxy matter which 

 covers different leaves ; but when we consider the . uni- 

 versality of the stomata among vascular plants, and the 

 rarity of these excretions, we are compelled to conclude 

 that if the stomata serve for their formation or produc- 

 tion, this can only be regarded as an additional use of 

 these organs. As for the cerous matter wiiich forms 

 the glaucous dust of plants, it offers a second objection; 

 it exists on several fruits, such as plums, for example, 

 which have no stomata. 



It is among the general functions of the foliaceous 

 organs that we must look for the office of the stomata ; 

 these orifices may then serve either for the exhalation or 

 the absorption of the air, or for the exhalation or ab- 

 sorption of water. 



As for their connexion with the evolution of gas, I 

 may remark, that their absence in roots and old stems, 

 their rarity in petaloid parts, and their obliteration in 

 parts which are etiolated, would seem to prove that they 

 serve for the exhalation of oxygen : since these different 

 organs are deprived of tliis function ; but, on the other 

 hand, they are absent in submerged leaves, fleshy fruits, 

 and all cellular plants. Now, as all these organs exhale 

 oxygen when they are green, we can only say that it 

 may be the stomata which fulfil this ofliice ; they exist 



