52 T. Holm — Croomia pauciflora. 



ground are leptocentric, and this structure is, also, to some 

 extent to be observed in the rhizome, but much less regularly ; 

 the following variations were noticed. A few were collateral 

 with the leptome and hadrome radially opposite each other and 

 supported by stereome on both faces, the outer and the inner. 

 Or the leptome was found to be surrounded by the vessels on 

 the sides, and these bordering again on other groups of leptome 

 with or without some support of stereome ; in others the lep- 

 tome constituted but one group with some vessels on the sides, 

 while inwards it was separated from the pith by layers of 

 stereome. Near the periphery of the cortex were observed 

 two isolated, collateral and, in transverse section, orbicular 

 mestome-bundles. 



The central portion of the rhizome is occupied by a thin- 

 walled, starch-bearing, solid pith. 



A much more regular structure exists in the short, vertical 

 internode below the uppermost of the three scale-like leaves 

 which surround the base of the flowering stem. In this inter- 

 node the fourteen mestome-bundles are located in an almost 

 regular circle ; nine of these are leptocentric and much larger 

 than the remaining five, which are collateral and orbicular in 

 transverse section. In regard to the disposition of these two 

 forms of mestome-bundles, there is usually a small one between 

 each two of the larger ones. They all are surrounded by 

 stereome and separated from each other. 



The stem. 



A like structure was observed in the long internode of the 

 stem above ground. This stem-portion is cylindric and solid ; 

 the cuticle is wrinkled and covers a small-celled epidermis, 

 which is moderately thickened, perfectly glabrous and almost 

 destitute of chlorophyll. The cortex consists of about four- 

 teen strata of which the peripheral three or six are collenchy- 

 matic, and the innermost layer did not show the characteristic 

 structure of an endodermis. A circle of thirteen mestome- 

 bundles is imbedded in the cortex ; each of these are com- 

 pletely surrounded by two to three layers of moderately thick- 

 walled stereome, which enters into the leptome as a separate 

 group in the larger bundles or merely as a bridge in the 

 smaller ones (fig. 1). The mestome-bundles are all more or 

 less oval in transverse section and contain a very large group 

 of small-celled leptome, completely surrounded by a ring of 

 scalariform and spiral vessels. 



A pith of large, thin-walled cells without starch occupies the 

 center of the stem. 



By continuing our investigation to the structure of the axis 

 of the inflorescence, we notice here the same arrangement of 

 the tissues, but the structure is somewhat weaker. There is 



