Organlzathn of Lea ves. \\\ 



membrane imlining itself. By adopting this idea I do not 

 know how we can explain the existence of lUricular inter- 

 stices, and assign a place to the air, since the parenchyma 

 of the leaves will be only a continued whole forJned ol cells 

 tlie sides of which are common. 



The utriculi arc lilled with a particular fluid which T call 

 the utricular juice. In leaves exposed to the action of light 

 the utriculi assume a green tint, which seems to depcnd^in 

 .an essential manner on small green globules w hich abound 

 in the juice, as seen iig. 15, where the utriculi of the fri- 

 tillaria are represented. These coloured globules are founc} 

 also in the utriculi of the stems ; and 1 have seen them 

 very distinctly in the cucurhita and irnp(eo/}uT?i, where 

 they are less numerous than in the leaves, but larger and 

 piore apparent. 



In the greater part of thick and fat leaves, the most in- 

 terior utriculi, which arc not coloured, seem to be desti- 

 tute of these globules, or at least if they exist they are not 

 sensible. 



In the utriculi of the bulb of the lily kind, and in those 

 of the root of the potatoe, these globules are very large, 

 often angular, but transparent and colourless. It is pro- 

 bable that they constitute the farinaceous part of these 

 jroots. 



I imagined for a long time that these globules were dis- 

 seminated in the utricular juice; but by ft more attentive 

 examination I found that they were applied to the mem- 

 brane of the utriculus without adhering to it, since, on tear- 

 ing som.e of the utriculi in water, I saw the globules di- 

 sperse themselves in the liquid. 



It is to these globules alone that Hedwig applied the dc- 

 poinination of parenchyme, as I have already mentioned. 



These globules engaged also the attention of Saussurc; 

 but he saw them only as small brilliant points, and the rc-» 

 searches he made to discover their intimate nature and uses 

 proved to be fruhless. 



This author detached from an asparagus-leaf a fragment 

 pf its bark ; and having viewed it with a microscope in the 

 light of the sun, either by rcflectiim or transparentlv, he 

 observed a multitude of small brilliant points nearly circular, 

 surrounded by an opake circle and almost contiguous ; the 

 first idea he conceived was, that the bark of the asparagus 

 was perhaps pierced with a multitude of small circular holes 

 which afforded a free passage to the sun's rays; but having 

 found a great quantity of tliese brilliant points in the 

 parenchyme and toilical r< ticulation, lu- concluded that thev 



did 



