MacDougal. — Symbiotic Saprophytism . 37 
peripheral layers of the stem are furnished with numerous 
yellowish-brown bodies which give the characteristic colour to 
the plant. The epidermis is composed of elongated spindle- 
form elements of the greatest irregularity of size and arrange- 
ment. The epidermis and the two underlying layers are 
slightly lignified, thus giving the shoot two distinct cylinders 
of lignified tissue. The outline of the epidermis is exceed- 
ingly crooked, and shows deep invaginations directly over 
large air-chambers, while in other places distinct fixed 
stomata are to be found. The surface is thickly covered with 
two forms of trichomes. In some places short lozenge-shaped 
cells are extended outwardly into club-shaped hairs septate at 
the base only, or prolonged into a number of ovoid cylindrical 
cells reminiscent of the staminal hairs of Tradescantia. The 
trichomes of the second type consist of a globular many-celled 
gland, borne on a stalk consisting of a central column of 
cylindrical cells and an outer circle of flattened elements, the 
entire structure being derived from a small group of epidermal 
cells. The gland is seen to be covered with a viscous secre- 
tion, the chemical composition of which could not be 
determined, since it was apparently dissolved from the alcohol- 
specimens brought to the laboratory. Whether the secretion 
is for the purpose of preventing the visit of unwelcome guests 
to the flowers or whether it bears some relation to the 
transpiratory processes, cannot be determined without further 
observation. Spores find lodgement in the secretion and 
germinate, penetrating the gland and its stalk, but never 
effecting entrance into the basal cells or the epidermis. 
The Scales. The scales near the base of the stem are 
smooth but with thin margins attenuated to form a fringe 
of stalked glands similar in structure to those found on the 
surface of the stem, except that the stalk is made up of 
a greater number of cells. The scales decrease in size 
upward along the stem. The basal scales are flecked with 
irregular patches of yellowish-brown areas, due to the 
penetration of the epidermal cells by brownish hyphae which 
completely fill them and extend over the surface of the 
