6 MacDougal. — Symbiotic Saprophytism. 
tion of their anatomy, with special attention to the chemical 
nature of the cells of the two organisms at the place of contact 
as well as to the substratum. 
Scope and Methods of Investigation. 
The work described in the following pages was undertaken 
for the purpose of extending knowledge of the occurrence 
of mycorhiza, the physiological relation of the two symbionts, 
the influence of mycorhizal arrangements upon the develop- 
ment of the higher plant with regard to the fate of a species, 
and the experimental formation and variation of such 
structures. Eight orchidaceous hemisaprophytes, two hemi- 
saprophytic Dicotyledons, one holosaprophytic Dicotyledon, 
and four autophytes were examined. The principal facts 
concerning each species are presented in separate sections, 
and no attempt has been made to carry the anatomical 
examination of the plants beyond the point of interest in 
connexion with the saprophytic habit exhibited. 
Aplectrum spicatum (. Aplectrum hyemale , Nutt.). 
Aplectrum spicatum is the sole representative of this North 
American genus of Orchidaceae, and it is found as far south 
as Georgia, as far north as the North-West Territory in 
Canada, extending across the continent. It finds most 
suitable conditions for growth in damp woods and swamps, 
in soils rich in humus. 
The plant consists of a compressed globoid corm of 
a glistening white colour, composed of three internodes. 
From the extremity of the upper internode arises a single 
elliptic or ovate leaf, 10-15 cm. long and 1-3 cm. wide, in 
July and August, and persists until late in winter, or until the 
following spring in southern latitudes. The base of the leaf- 
stalk is sheathed by three scales, 3-7 cm. in height. The 
peduncle arises from the first internode in May or June, 
attaining a length of 25-50 cm., bearing three scale-leaves 
and a terminal raceme of dull yellowish flowers. One or two 
