24f VEGETABLE ORGANOGRArHY. 



a loose and succulent tissue ; but their situation and 

 history are still very obscure, and deserve to occupy 

 most particularly the attention of anatomists. We will 

 return to this subject in speaking of the Air cavities, and 

 Receptacles of proper juices. 



It must be seen from the foregoing, that the principal 

 property of the cellules or vesicles forming the cellular 

 tissue, is the faculty of uniting together. This property 

 plays an important part in the whole history of vege- 

 tation : not only to its different degrees are all the 

 internal appearances of the tissue to be referred, but 

 also it is these combinations of the cellular tissue that 

 cause all the combinations of the different organs, which, 

 at first being distinct, finally form a single texture, in 

 appearance simple, in reality compound. 



A second peculiarity of the tissue of the cellules is, 

 that they are eminently hygroscopic ; that is to say, that 

 they absorb water with which they may be in contact, 

 and in particular that which is conveyed by the Inter- 

 cellular passages. Probably this water, deposited in the 

 cellules, undergoes a particular elaboration, from which 

 results the formation of the substances which are ob- 

 served in them. This hygroscopic property has appeared 

 to me for a long time, as it did to Senebier, to be one 

 of the principal bases of the phenomena of vegetable 

 life. Eaeser has also insisted, on a later occasion, upon 

 its importance. 



Finally, the third property of this tissue appears 

 to be organic contractility ; a phenomenon purely phy- 

 siological, which I ought only to mention incidentally 

 in this place, but without which it is difficult and perhaps 

 impossible to comprehend the course of the sap. 



