Mac Doug a l. — Symbiotic Saprophy tism. 
27 
Pogonia ophioglossoid.es (L.), Ker. 
This plant grows in moist humus. The roots are few in 
number, arising from a short underground stem, and attaining 
a length of 3 to 8 centimetres. The epidermis consists of 
polygonal cells bearing very large root-hairs which are seen 
to be traversed by hyphae. The exodermis is mostly 
thick-walled, though here and there thinner-walled passage- 
cells are found. The four to six layers of cortex abound in 
hyphae. Numerous large vesicles are formed which are 
generally closely appressed to the nucleus. Invagination of 
the nucleus may progress so far as to give it a reniform 
appearance, yet in every instance it stains deeply, is greatly 
enlarged and apparently benefited by the presence of the 
Fungus. 
The endodermis is not clearly defined, and the conducting- 
tissues are but moderately developed. The hyphal clumps 
are persistent even in members in which disintegration of the 
cortical layers has begun. The cells containing the hyphal 
clumps are distributed indiscriminately with others loaded 
with starch. The Fungus penetrates the cortical layers of 
the stem in rare instances, and the underground portions 
show conical or papillose extensions of the epidermal cells 
which would give a greater surface in contact with the 
humus. 
Gyrostachys cernua (L.), Kuntze ( Spiranthes cernua , L.). 
The roots are cylindrical, nearly straight, 2-3 mm. in 
diameter, and a few centimetres in length, spreading out 
horizontally through the loose substratum. The apical 
portion is whitish, but the older sections are brownish with 
irregular patches of adhering humus. The shoot is furnished 
with a number of bract-like green leaves showing some 
variation in size. 
The epidermal system of the roots is composed of three 
layers. The outer layer consists chiefly of shallow cup- 
shaped cells, with the outer walls concave and cuticularized. 
