398 BOTANICAL GAZETTE [DECEMBER 
It might be well to add that the habitat of the prothallia of 
this species of Lycopodium is somewhat more shaded, more moist, 
and more protected from sunlight than that for L. clavatum, L. 
complanatum, and L. annotinum. The prothallia of five species 
have been found within a few centimeters of each other, however. 
They are most abundant at a depth of 1 cm., and seldom grow at a 
depth of more than 2cm. Very frequently they occur upon the 
surface of the ground. The habitat of these prothallia agrees in 
all essential respects with that for ZL. Selago, with the exception 
already mentioned, which seems to indicate that they require a 
slightly drier place for growth than do those of the latter. 
DESCRIPTION 
The older regions of the prothallia are brownish, while the 
young growing tips as well as the very young prothallia are white. 
It is these very white tips that are first noticeable when digging in 
the soil. They are closely beset with multicellular hairs (fig. 49), 
which in some cases include as many as five cells. They are evi- 
dently of a glandular nature, for in fresh specimens of prothallia 
the region which bears them is covered with a thin mucilaginous 
secretion slightly denser than water. If the prothallia are placed 
in water, this substance quickly swells and is dissolved. What- 
ever its nature, no doubt it plays the important réle of keeping the 
young growing region and the young sex organs from becoming dried. 
None of the fungus filaments which closely adhere to the exterior 
of other parts of the prothallium ever pierce it, nor do soil particles 
or leaf mold adhere to it. It is probable that the growing apical 
region is lubricated sufficiently by this substance to prevent injury 
during its upward passage through the soil and mold, which are 
often very compact and solid. 
The adult prothallia vary very much in size and shape (cf. 
figs. 2-41). These figures are all drawn to a scale of four, so that 
they are just twice the size of the original specimens. 
The form of the prothallium does not conform exactly to that 
of any type heretofore described. It approaches nearest that of 
L. Selago described by Brucumann. Taking fig. 15 as the type 
form, it will be noticed that there is a lower cup-shaped primary 
