366 ELEMEN 7 TARY ORGANS. CHAP. III. 



of plants, and with the assistance of the best mi- 

 croscopes, but all in vain, not having been able to 

 detect them in any one instance.* 



This might be thought to throw a degree of 

 doubt upon the accuracy of Hedwig's observations. 

 But M. Decandolle, who has also investigated the 

 subject with great care, establishes the fact of the 

 existence of the pores in question, in the most sa- 

 tisfactory manner, and introduces much of new 

 and additional remark ; regarding them as being 

 connected with the ultimate ramifications of the 

 leaf-stalk, as dispersed throughout the parenchyma, 

 and grounding his opinion upon the appearances 

 exhibited in the leaves of Crassula punctata, 

 lactea, and Cotyledon. He believes them to be 

 organs of insensible perspiration, and observes that 

 they are never to be met with on the nerves of the 

 leaf, where external hairs, on the contrary, are al- 

 ways situated. He adds, that no pores are to be 

 found upon the stalks of any plants, except such 

 as are of a soft texture approaching to that of 

 leaves ; nor upon fleshy fruits, such as Pears, 

 Peaches, Gooseberries ; nor upon roots ; nor upon 

 the bulbs of liliaceous plants ; nor upon plants 

 really acotyledonous ; nor upon plants that are 

 wholly submersed. ~}~ The general accuracy of the 

 above statement is farther confirmed by the observa* 



* Phys. Vcg. vol. i. p. 456. 



f Journ. do Phys. torn. iii. p. 130- 



