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MacDougal: Symbiosis and Sapropiiytism 517 



The rhizome exhibits no marked or general degeneration, unless 

 the condition of the phloem could be interpreted in this manner. 

 The xylem is amply developed for the conduction of the supply 

 of water necessary for the aerial shoot, and the elongated elements 

 near the vessels appear to be suitable for the transmission for pro- 

 teinaceous compounds, a function served by certain cells immedi- 

 ately internal to the endodermis in the root. The rhizome of 



Ccpl 



sapro- 



phytes in not being provided witli organs for the excretion of water. 



The Ixflorescexce 



The flowering stem is composed of flattened internodes 2 to 5 

 cm. long, bearing short sheathing leaves, and a terminal raceme 

 of flowers. The epidermis is composed of flattened cylindrical 

 elements with oblique ends, resembling tracheids in general form, 

 and with the inner and radial walls dotted with numerous perfora- 

 tions. Irregular masses, globules and networks of a yellowish 

 brown substance are abundant in the epidermal and cortical cells 

 of material preserved in alcohol. Ordinary chemical tests arc 

 without definite reaction, though Raspail's reagent gave slight in- 

 dication of proteids in these masses. The epidermis is totally 

 devoid of transpiratory openings. 



The cortex is eight to twelve layers in thickness, and consists 

 of elongated cylindrical elements with no intercellular spaces. It 

 appears^o serve as a tissue for the storage of water. Internal to 

 the cortex is a sclerenchyma sheath, in the inner margin of which 

 lies a circle of 32 to 40 bundles, and centrally placed is a second 

 ring of six to eight bundles, which are fairly identical with those 

 of the rhizome. Each bundle is enclosed in its own schlcren- 

 chyma sheath. The sheath and the xylem are heavily lignified. 

 No marked degeneration is to be seen outside of the lack of chlo- 

 rophyll, the transpiratory organs, and the intercellular spaces of 

 the cortex. The heavy sclerenchyma sheath is a feature of the 

 aerial stems of the symbiotic saprophytes. The xylem shows a 

 very typical development. 



The Leaves 

 The leaves are reduced to sheathing bracts, and are destitute of 

 chlorophyll, as shown by an examination of the alcoholic extract 



