of the Organs calkd Lenticels. 275 



epidermis dries and grow old ; but I have never seen them pass 

 to the state of lenticels. On the other hand, in the short hairs 

 already mentioned, and which are, properly speaking, elevations 

 or pouches of the epidermis, the following facts may be ob- 

 served : the upper part of the short hair, or the centre of the 

 obtuse epidermic process, dries up and becomes destroyed at a 

 certain time, and there soon remains nothing but the base, 

 which is of an oval or elliptical form, and the margins of which 

 are composed of a delicate membrane with lacerated edges ; in 

 place of the hair a narrow hssure only is then seen. It is 

 through this fissure that the eruption of subepidermic cellular 

 tissue of which the adult lenticel is composed, takes place; the 

 quantity of cellular tissue ])rotruded soon enlarges the original 

 fissure by tearing it, and the origin of the lenticel is no longer 

 recognizable ; subsequently the increase in the length and dia- 

 meter of the branch and the consequent distension of the epi- 

 dermis become fresh causes of deformation, and the lenticel, after 

 having been torn in a vertical direction, becomes enlarged hori- 

 zontally. The cellular mass of suberose appearance which pro- 

 trudes through the epidermic fissure in the form of a double 

 cushion, and of which the outer layer becomes brownish by de- 

 siccation, appears to me to be composed, not of the herbaceous, 

 or deep cellular layer, but of the suberose or subepidermic cel- 

 lular layer. 



In the suberose variety of the Elm, the first development of 

 the lenticels takes place as in the Elder, but the excessive hyper- 

 trophy of the subepidermic cellular tissue soon disguises its len- 

 ticellar origin. In this tree I have followed all the transitions 

 between the first elevation of the epidermis, the lenticellar hernia, 

 and the corky masses which afterwards cover the bark with their 

 anastomosing channels. In this tree, as in the preceding, nu- 

 merous microscopic preparations have always showed me a per- 

 fect continuity between the lenticellar hernia and the suberose 

 layer of the "bark, with this difference, that in consequence of 

 the direction of the expansion, the cells of the protruded portion 

 are perpendicular to the bark instead of being parallel to it, as 

 in the normal suberose layer. 



From these observations it results that I regard the lenticels 

 not only as a formation analogous to cork, but as one completely 

 identical in origin and in tissue : the difiFerence between the two 

 productions consists only in the intensity of the hypertrophy, 

 which is generally feeble in the production of lenticels and very 

 intense in that of cork, which is nothing but exaggerated lenti- 

 cellar production. 



The maceration in water, or insertion in moist earth, of 

 branches covered with lenticels, has convinced me, like M. 



