8 Researches respecting the 



tances, has fascinated the eyes of observers. The mem- 

 branes which form the sides of the cells have always been 

 taken for vessels or for fibres." 



The utriculce \\ hich compose the surface of the leaves 

 have in general a form different from that of the utriculae 

 of the parenchyme, and a direction which is often opposite 

 to them. In iht J'rU/Uaria, for example, the form of the 

 exterior utriculae approaches that of a parallelopipedon very 

 much elongated, in the direction of the length of the leaf 

 (fig. 1. A, and fig. 5.), while the interior utricula; are nearly 

 spherical, as seen in fig. 7, 8, and 15. 



The erythrovhim dens cants has its exterior utricular also 

 elongated in the direction of the length of the leaf ; they 

 cross at right angles those of the parenchyme, which are 

 cylindrical, and which consequently have their direction 

 according to the breadth of the leaf. This disposition is 

 not well obsen'ed but in the superior surface of the leaf. 



The leaves of the lavatt-ra triloba have their exterior utri- 

 culic festooned like those of fig. 1-1; but the interior ones 

 exhibit the form of a cylinder, the length of which is in the 

 direction of the thickness of the leaf. 



The exterior utriculaj of the leaf of the silphium peifo- 

 liatum are also festooned ; while the utricuhe of the paren- 

 chyme are cylindric on the superior side of the leaf, and ir-i 

 regular on the inferior, like those of fig. 18. 



In the orchis maculata the exterior utriculae of the leaf 

 are remarkable by their size, and particularly by theip 

 height : they alone constitute a great part of the thickness 

 of the leaf. 



I might multiply these examples; bvit I think I have said 

 enough to prove what I have advanced, namely, that the- 

 extenor utriculte of the leaves are in general very different 

 froiTi the utriculae of the parenchyme. 



Having examined the existence of the epidermis and that 

 of the lymphatic vessels which form the cortical reticulation 

 of the leaves, I shall proceed to the cortical glands of Saus-t 

 sure, or the evaporating pores of Hedwig; but I shall first 

 say a few words of the manner in which the exterior utri- 

 culae of the petals present themselves, 



In most flowers the exterior utrieulas of the petals arc; 

 conical ; they rise in the form of teat-s, more or less promi- 

 nent, on which the rays of light are broken and reflected n\ 

 such a manner as to produce to our eves that dark rich vel-i 

 vety appearance which gives them so beautiful an aspects ,. 



To give *n idea of l,he eflect. pi-oduced by thest; niaiujntlT 



