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907] HOLM—RUBIACEAE 163 
nating with two broad strands of leptome, and no increase in thickness 
takes place. A corresponding structure was observed in the capil- 
lary lateral roots, with the exception that the various tissues are much 
less developed, the cortex consisting of only two layers, the endo- 
dermis being thin-walled and the hadrome being reduced to a very 
few vessels. 
The stolons.—The stretched internode is perfectly glabrous, and 
obtusely quadrangular to almost cylindric. A smooth, quite thick 
cuticle covers the epidermis, which is thick-walled and contains 
chlorophyll. There are four layers of compact cortical parenchyma 
with chlorophyll, and the endodermis is moderately thickened and 
contains starch. The stele is represented by a confluent zone of lep- 
tome and vessels in about five rows, with narrow medullary rays of 
mostly one row of cells. A thin-walled pith occupies the center and 
contains starch, but no raphides were observed. 
The aerial stem.—The long internodes are glabrous, quadrangular, 
and four-winged. In these the cuticle is wrinkled, and the outer cell 
walls of the epidermis are quite thickened. Stomata are frequent; 
they are level with the epidermis and have a wide air chamber. The 
cortical parenchyma consists of four strata between the wings, but of 
eight in them; no mechanical tissue, neither stereome nor collenchyma, 
was observed. A thin-walled endodermis surrounds the collateral 
mestome strands and the pith, which is narrow and very thin-walled. 
The peduncle.—There is here about the same structure as in the 
long internodes, but the outline is simply quadrangular. The cortex 
represents a narrower zone, and the stele consists of several more or 
less separate mestome strands, but in one circle and collateral as 
above; the medullary rays are very distinct and the central pith 
somewhat wider. 
The leaves.—The basal leaves, which winter over, have a very 
distinct petiole and a blade that varies from spatulate to almost 
ovate. Viewed en face the blade shows a perfectly smooth cuticle, 
and the lateral cell walls of the epidermis undulate on both faces. 
Stomata occur only on the lower face (fig. 7), and they have a pair of 
subsidiary cells parallel with the stoma. Unicellular hairs with the 
cuticle spirally thickened (fig. 5) are to be observed along the margins, 
while bicellular hairs with similar spiral striations are distributed over 
