300 Holm — Studies in the Cyperacece. 



in contrast to the partly discolored involucral leaves. The 

 epidermis of the upper face consists of very large cells, which 

 cover the entire surface, excepting near the margins, where a 

 relatively large group of stereome is located, above which the 

 epidermis-cells have become very small. The upper face of 



the blade is thus covered with 

 bulliform-cells, in which respect 

 our plant reminds us somewhat 

 of Cyperus fuscus, which has 

 been described and figured by 

 Duval-Jouve (I.e. i). The cells of 

 the epidermis of the lower surface 

 are much smaller, and their walls 



Fig. 1. Transverse section of the are slightly undulate ; we find, 



B le c. tV^buSrm-Ss. 15 x aIso > here the internal cones, which 

 natural size. seem to be constantly developed 



in the epidermis, which covers the 

 stereome. Stomata are to be observed on this, the lower sur- 

 face; they are not very prominent, and they form longitudinal 

 bands underneath the mesophyll. This last tissue occupies a 

 very large part of the blade and consists of rather closely 

 packed palisade-cells on the lower surface, while it shows a 

 more open tissue on the upper face, just underneath the bulli- 

 form-cells. We notice, therefore, that the palisade-tissue and 

 the stomata are exclusively restricted to the lower face of the 

 leaf-blade, a fact which seems due to the extraordinary develop- 

 ment of the upper epidermis. The palisade-cells are mostly 

 arranged vertically upon the leaf-surface, but we have, also, 

 observed an approximately radial arrangement around the 

 mestome-bundles. The cells of the mesophyll near the upper 

 surface are polyhedric and leave room for numerous, but small, 

 intercellular spaces. While only a few cells of the lower 

 epidermis contained tannin, the mesophyll was observed to 

 possess quite a number of such reservoirs. Very distinct and 

 well differentiated from the mesophyll is the colorless par- 

 enchyma-sheath, which borders on the mestome-bundles and 

 partly surrounds these. We have seen from previous studies 

 that this parenchyma-sheath is generally interrupted by the 

 stereome in the large mestome-bundles, while it forms a closed 

 ring around the smallest ones, which as a rule are not in con- 

 tact with the hypodermal groups of stereome. Dichromena 

 forms, however, an exception to this rule, since, as we shall 

 see later, the colorless parenchyma-sheath does not surround 

 even the smallest mestome-bundles, but is, also, here interrupted 

 by small stereome-elements, widely separated from the epider- 

 mis of both faces of the leaf-blade. Inside the colorless 

 parenchyma-sheath is the usual mestome-sheath, which is here 



