252 



VEGETABLE 



witli their summits truncated, or cut off, Fi s- 222 

 as lepresented by Fig. 222. In some 

 instances, these figures are not elonga- 

 ted, as here represented, but the sides 

 ajo equal, forming when cut across, the 

 appearance of a net-work like the cells 

 of a honey-comb. 



In some plants, when the stem is di- 

 vided longitudinally, these cells appear 

 in the form of elongated tubes, or cylinders, as represented 

 by Fig. 223. 



It has been disputed whether the cells of vegetables are 

 closed on all sides, or whether they communicate with each 

 other. Mirbel has given delineations of what appeared to 

 him to be pores and fissures, communicating between the 

 cells. But subsequent observations have rendered it most 

 probable that these appearances arise merely from darker por- 

 tions of the membranes, where opaque particles have been 

 deposited in their substance ; and it is now understood that 

 fluids gain access to these cells by transuding through the 

 membranes which form their sides, and not by apertures 

 capable of being detected by the highest powers of the mi- 

 croscope. 



If the cells of vegetables consist of separate vesicles, as 

 the concurring observations of modern Botanists, (Kieser, 

 Link, Amici, Dutrochet, and Decandolle,) appear satisfactorily 

 to have shown, then the partitions which separate them, how- 

 ever thin, must consist of a double membrane, formed by the 

 adhesion of the two coats of the two contiguous vesicles. 

 But as these coats can hardly be supposed to adhere at every 

 point, it is most probable, it will hereafter be found, that spa- 

 ces have been left, in various parts between them, and that 

 communications exist to a certain extent between all these 

 spaces, so as to compose what may be regarded as one con- 

 tinuous cavity. These are termed the intercellular spaces ; 

 and they have been supposed to perform an important part in 

 the function of nutrition. 



Fluids of different kinds, occupy both the cells, and the in- 

 tercellular spaces. The contents of some, is the simple 

 watery sap, and that of others, the products of vegetable se- 

 cretion ; in many instances they contain air only. 



In the cells of some vegetables, there are found small, 

 opaque, and detached particles of the substance termed 

 Fccula, by chemists, and which, when separated, form 



