204 PROCESS OF DEVELOPEMENT. CHAP. IV. 



viewed it in a light altogether different, and have 

 regarded it as being merely the effect of accident, 

 and nothing more than a scurf formed on the ex- 

 terior and pulply surface of the parenchyma indu- 

 rated by the action of the air. This was the opinion 

 of Grew and Malpighi, which, though it does not 

 seem to have ever met with any very general recep- 

 tion, has been, however, revived of late by M. 

 According Mirbel ; who, professing to be dissatisfied with the 



to Mirbel. 



analogy that has generally been thought to exist 

 between the epidermis of the animal and vegetable, 

 contends that the latter is nothing more than the indu- 

 rated surface of the parenchyma, from which it differs 

 only in such circumstances as are occasioned by posi- 

 tion. If it is more or less transparent if it is tougher 

 end firmer in its texture than the parenchyma or 

 any of its parts, it is only because it is constantly 

 exposed to the influence of light and air, and to the 

 contact of such bodies as float in the atmosphere ; 

 but it is not to be regarded as constituting a distinct 

 organ or membrane, or as exhibiting any proof of 

 its being analogous to the epidermis of animals.* 

 Such is the substance of M. MirbeFs opinion, to 

 which he is aware that objections may still be 

 urged. For it may be said, if this is the true origin 

 of the epidermis, how comes it to separate so easily 

 from the interior parts in the spring? To this ob* 

 jection M. Mirbel furnishes the following reply- 

 namely, that its facility of detachment is owing to the 

 * Traitc d'Anut. ct de Phys. Veg. torn. i. p. 87. 



2 



