HISTOLOGY OF LONICERA SKMPERVIRKNS. 



507 



Palisade in one or two layers of rather short cells, passing without 

 sharp demarkation into the open pneumatic tissue. 1 



Mestome bundles completely embedded in the chlorenchyma, 2 each 

 surrounded by a one-layer sheath of delicate, small-celled, colorless 

 parenchyma. Collenchymatic hypodermal parenchyma in small quan- 

 tity beneath the midvein. 



Stem four-angled, the angles winged, the wings composed of strong 

 peripheral groups of thick-walled stereome, and of compact chloren- 

 chyma toward the circumference of the stem proper. Mestome cylin- 

 der entirely surrounded by a thin- walled endodermis. Medullary rays 



Fi<;. '.ni- (i<i,,u,f. ni.,ptuu.uiiL, leaf, it ami b, Hairs from upper surface; c, portion of lower 

 epidermis showing stnmata as secretion colls. Magnified M times. 



very narrow. Pith occupying the center of the stem, finally breaking 

 down and producing a lacuna. 



LONICERA SEMPERVIRENS L. 



In various situations, but most abundant on the inner sand dunes. 



Leaf bifacial, dark green above, glaucous beneath, more or less per- 

 sistent, midvein prominent beneath, under surface sparsely pubescent 

 when young. 



Epidermis; Ventral, radial cell walls straight, thin; cuticle very 

 thick, roughened. Dorsal, cell walls thin, the radial undulate; cuti- 

 cle bearing a coating of wax. Stomata confined to the dorsal surface, 

 small, numerous, lying in all directions, level with the surface, each 

 bordered by four or five ordinary epidermal cells. Hairs numerous 



' • ■ Raphides-holdinir cells occur in the mesophyll beneath the palisade, and some- 

 times in the parenchyma of the nerves of all Galieae studied."' Vesque.loc. cat., 

 p. l!);i. I did not detect raphides in the leaves or steins of (!. hispidulum. 



4 "In general the bundles [in Rubiaceae] are completely immersed in the meso- 

 phyll; that id to say, the tissues pass above and below the bundles without under- 

 going the least change." Vesque, loc. cit.,p. 202. 



