Organization of Leaves. 113 



«een to issue from all the proper vessels a viscous and trans- 

 parent juice, which contains a multitude of these prismatic 

 filaments, which give to this juice an argentine colour. 



Rafn, in his Physiology of Plants, says he found small 

 prisms in the milky juice of the euphorbia. I found them 

 also, but only in small number. 



What are these prismatic filaments ? How are they 

 formed ? Why are they found in some plants and not in 

 ©tilers ? In the last place. What is the use of them ? These 

 pre questions which it is impossible for me to answer, and 

 respecting which I have no data. I shall now proceed to 

 the communication of the utriculi with each other. 



Senebier says that " the utriculi form a kind of vesseljj 

 composed of vesicles bound together. They have a pretty 

 exact resemblance to a flexible tube, slightly choked at di- 

 stances nearly equal, and nevertheless retaining a free com- 

 munication throughout the whole length of the canal." 



C. Mirbel discovered that " the membranous sides of 

 the cellular tissue are in general perforated with pores, the 

 apertures of which are certainly not the hundredth part of ^ 

 line ; that these pores are bordered with small, unequal, and 

 glandulous rolls, which intercept and strongly refract the 

 light when they receive its rays ; that they establish a com- 

 munication between one cell and another, and serve for the 

 transfusion of the juices, which in this tissue is exceedingly 

 slow. 



To ascertain whether there was a direct and sensible com- 

 munication between the utriculi, I employed various means. 

 I cut a very thin piece of the parencliyme of the leaf of the 

 fritillaria, which 1 chose in preference on account of its 

 spherical utriculi, which are frequently united by a pro- 

 longation in the form of a neck, fig. 15, and which on that 

 account have a greater resemblance to the choked tubes 

 jmentioned by Senebier. I placed it in the focus of the mi- 

 croscope ; and having o!)served several coinplete utriculi, 

 I compressed one of them slightly with a very fine needle, 

 presuming that the liquid it contained would pass imme- 

 diately into those adjacent to it, and which were open : but 

 the pressure I continued to exercise on it made it burst, 

 and the juice it contained was instantly dispersed. I re- 

 peated this operation several times, following very attert- 

 tively tltc impulse of its utricular juice that 1 might ob- 

 serve Its passage into the neighbouring utriculi, which, in 

 my opinion, would have taken place had. a free cpmmum- 

 galion existed between them. 



I repeated this experiment on other J^avos the utriculi 



Voi.. XVI. No. 62. a of 



