9 
MacDougal. — Symbiotic Saprophytism. 
bundles of hyphae closely resembles those of Corallorhiza 
as figured by Thomas (37), except that the filaments are 
much more closely interwoven and curve more abruptly. 
It is noticeable that the hyphal masses may occupy ail the 
cortical cells from the exoderm to the endodermis. The 
nuclei to which the myceliar masses are appressed are usually 
enlarged and hyperchromatic. The increase in size is accom- 
panied by an enlargement of the nucleolus and the assumption 
of an irregular globoid or oblong ovoid form, although the 
actual outline is smooth and curving. The presence of the 
Fungus does not appear to affect the nucleus unfavourably. 
These endotropic hyphal clumps are found intact in old roots 
in which the ectotropic Fungi and the epidermal cells have 
decayed. 
The endodermis consists of brick-shaped cells with walls 
not thickened to any appreciable extent. The stele is 
tetrarch. Each bundle consists of two to four scalariform 
ducts, and a number of libriform vessels with transverse 
pores. The number of bundles increases to six or seven 
in old roots, and the conjunctive tissue becomes strongly 
sclerotized. 
At the beginning of the growing-season some variations 
from the features described above were to be seen. At this 
time the cortex is heavily loaded with starch, giving the 
typical iodine-reaction. The hyphal clumps give a yellowish 
brown reaction with the same reagent. Great numbers of 
highly refractive and vacuolated hyphae are to be seen which 
stain yellowish with iodine, and these apparently break up 
into globose bacterioids staining reddish brown. The ulti- 
mate fate of these bodies is yet to be determined. Lateral 
branches of the hyphae develop into stalked globules of 
a diameter three or four times as great as the filament. The 
granular contents stain a deep reddish brown with iodine. 
These formations are to be seen occasionally in the medio- 
cortex, frequently in the epidermis, and rarely in the root- 
hairs. In the last-named instance the entire cavity of the 
hair may be thus occupied. The structures in question may 
