KNOWLEDGE OF MONOCOTYLEDONOUS SAPROPHYTES. 151 
abnormal in structure. The peculiarities arise from the changed 
grouping of their constituents or from their reduction. 
As will be seen later on, some of these generalizations remain 
no longer true. 
Special Work on Orchidaceous Holosaprophytes. 
History.—A brief summary of our knowledge concerning the 
histology of orchidaceous saprophytes may be formed by a refer- 
ence to the accounts of Corallorhiza, Epipogum, Neottia, Wull- 
schlegelia, and Pogoniopsis. 
In Corallorhiza innata and Epipogum aphyllum the plant con- 
sists of a subterranean rhizome and a flowering axis. (There 
may be a small remnant of a root—'* Keimaxe ” P) 
CoRALLORHIZA INNATA is said to possess chlorophyll in small 
quantity. The rhizome has small scale-leaves; and on it are 
small conical papille which bear hairs functioning as root-hairs. 
An epidermis covers a cortex which is differentiated, according 
to Reinke, into three portions :— 
(1) An outer portion composed of cells containing hyphe and 
starch. 
(2) An intermediate portion the cells of which contain yellow 
slime (mycelial masses, P.G.) but no starch. 
(3) Aninner portion again containing starch. Here and there 
radial strands of starch-containing cells connect the inner and 
outer portions of the cortex. Starch disappears from the rhizome 
as the inflorescence-axis shoots up, but reappears as the fruit is 
forming. 
An endodermis surrounds the central stele of the rhizome. 
Within this Reinke describes two groups of spiral vessels and 
3-5 groups of phloóm on the same or on different radii. The 
phloém, he says, is composed of narrow prosenchymatous cells 
with somewhat thickened walls which are separated from the 
endodermis and from the wood-vessels by cells with delicate walls. 
A single vascular bundle runs from each scale on the rhizome, 
and consists of wood-vessels surrounded by phloém-cells. 
In the znflorescence-axis a general sclerenchyma-sheath includes 
a single circle of vascular bundles. Each bundle is composed of 
phloém-cells which surround and separate one to two groups of 
wood-vessels (Reinke). 
In Eprpoaum APHYLLUM the scales on the rhizome are more 
M 2 
