NYMPEJUACEuE. 95 



ference, rise vertically and follow a more or less oblique course 

 through the stem to reach the leaves. At the same time adventitious 

 roots, " also with the structure and growth of Monocotyledons," 

 appear on the rhizome at the bases of the leaves. 1 Moreover, the 

 parenchyma, both of rhizome and petiole of NymphceetB and 

 Nelumbece, is traversed by enormous lacuna?. These contain gas, 

 with whitish masses of irregular mammilla ted cells projecting inside, 

 and the so-called radiating or stellate cells, with their rays free in 

 the cavity to whose wall their centre is fixed. These have been 

 considered as organs of support for the different parts of the 

 parenchyma ; 2 in the leaves the rays extend so far that their points 

 reach the epidermis. Stomates are only to be found in the 

 Nym/phaem on those parts of the foliar epidermis which are in con- 

 tact with the air — i.e., the upper surface, in the species with floating 

 leaves. The lower surface bears either hairs, or in Euryale prickles, 

 the largest of which contain longitudinal fibres and vessels, and end 

 in a pore or osteole, which is probably an organ of absorption. 3 The 

 leaf blade of Victoria is also completely traversed by narrow holes 

 termed stomatodes. 4 Several Nymphceacece also contain laticife- 

 rous vessels, tubular, continuous, cylindrical and more or less irre- 

 gular. 4 



The histological structure of the Cabombea seems correlated with 

 their habitat. The submerged parts contain no true vessels, 6 but 

 instead of these more or less elongated cells of variable form, 7 con- 

 stituting a small number of bundles 8 (usually two) in the stem and 

 branches. Outside is seen a parenchymatous tissue, which is here 



1 "Nothing in theroots of a Ntiphar reaih those hedral tuberosities. The form varies greatly 



of a Dicotyledon. They have no distinct bark, with the position and the species under obser- 



any more than the stem, nor anything comparable vation. 



to medullary rays. Their whole structure is, on 3 The same author shows Planchon "over- 



the contrary, comparable to that of a Monocoty- stepped the truth in saying that the weakest no 



ledonous root " (Te£c), in Ann. Sc. Nat., ser. less than the strongest of these prickles contained 



3, iv. 304. vessels ; they are confined to the strongest." 



' 2 Te£cul has studied the development of these * Pl., in Fl. des Serres, vi. 249. — Tafc, loc. 



cells, which had been described by Guettaed in cit., 158. 



1747, Amici, Rudolph, De Candolxe, Meyen, 5 Tk£c., loc. cit., 159. 



Mirbel (in Ann. Sc. Nat., ser. 3, iv. 314, t. 12, . 6 Schleid., in Wiegm. Arch., ix. 230. — 



fig. 19, 25). He saw that at their origin they Lindl., Teg. Kingd., 412, fig. 289. 



were placed between two neighbouring cells, and ' Sometimes fusiform, sometimes cylindrical 



formed a triangular cell, with its angles at first and truncate at either end ; no spiracle is found, 



obtuse, and then elongated and ramified ; smooth s Usually two, as Brasenia and Calomba; 



at first, the cell was afterwards covered with poly- and these are often but slightly distinct from the 



