24 MacDougal. — Symbiotic Saprophytism . 
Cypripedium hirsutum (Cypripedium pubescens, Willd.). 
The roots of C. hirsrltum present the same general features 
as those of C. parvijiorum , except that they are larger. The 
fungal filaments occupy the same layers, but are more 
copiously developed, and stain more deeply. In neither this 
nor the preceding species were any hyphae found outside 
the root. The hyphal convolutions in C. parvijiorum fuse to 
form a ‘ vesicle-like ’ absorbing organ by the nucleus ; but in 
this species the loosely-arranged mesh-character is preserved. 
The presence of the Fungus appears to be indifferent or 
perhaps in some instances parasitic, as certain included nuclei 
stained less deeply than the typical form. 
Cypripedium acaule (Ait.). 
The roots of C. acaule are large, 2 to 3 mm. in diameter, 
curved in an undulating manner, and attain a length of 8 to 
15 cm. The epidermal layer, like that of C. hirsutum and 
C. parvijiorum, is yellowish brown except in the very youngest 
portions, owing to the presence of colouring matters in the 
outer wall. The epidermal cells are irregular in the surface 
outline, and flattened oval in cross-section. The exoderm is 
composed of four- or five-sided, small, thin-walled cells. The 
cortex consists of nine to twelve layers of large cylindrical 
or globose elements rich in starch. Scattered at random 
through this tissue are clumps of hyphae almost filling the 
cells. A few vesicles are formed near the nuclei, and the 
hyphae may be traced through the exoderm and epidermis 
in a manner similar to that figured by Janse (PI. IX, Fig. 14). 
The endodermis is ill-defined and consists of thin-walled 
elements. The central cylinder shows nine to twelve groups 
of xylem with great centripetal development, and a relatively 
large cross-section of conducting-tissue. The Fungus does 
not gain entrance into the stem-structures. 
The nuclei of the cells inhabited by the Fungus are 
above the normal in size and stain deeply. No considerable 
