400 BOTANICAL GAZETTE [DECEMBER 
far from being typical, as the drawings to the left of it show. Even 
in fig. 32 the sex organs occur on one side, while the vegetative 
organs are mainly opposite and lateral to it. Apparently the only 
difference between the form of the prothallia of the two species in 
question is the alleged conical shape of L. Selago prothallia, and I 
am not able to see that BRUCHMANN’s figures admit even of this 
difference. If I were to use the same method of drawing as he has, 
_ it would be almost impossible to distinguish between the typical 
forms of prothallia of the two species. BRUCHMANN’S figs. 22, 28, 
and 29 are especially easy to match with prothallia of L. lucidulum. 
My figures merely accentuate the different regions of the prothallia, 
while his suggest them. 
For the present, therefore, the prothallium of L. lucidulum is 
placed with BrucHMANN’s type for L. Selago, but it is probable 
that the necessity for such a type is one of convenience rather than 
a morphological one. For the sake of reducing the growing number 
of types of prothallia for the genus Lycopodium, it might be well 
to include these representatives of the L. Selago type in the L. 
clavatum type. 
Chlorophyll occurs regularly and abundantly in the subepidermal 
cells of all prothallia of L. lucidulum which were found growing upon 
the surface. Four prothallia were found which had bifurcated. 
The age of the prothallia varied greatly, as the figures show. There 
seems to be some evidence that the prothallia of L. lucidulum have 
a much shorter period of development than BrucHMANN found for 
his European species. Solely from field observations I should 
estimate that adult prothallia for L. lucidulum probably mature 
within two or three seasons, but the period for L. obscurum must be 
much longer. 
TISSUES 
A longitudinal section of a prothallium like that shown in fig. 50 
shows two main regions, an upper and a lower. The upper region 
is divided into a distinct epidermis, which bears the sex organs and 
paraphyses, and a subepidermal mass of cells of parenchymatous 
structure which contain chlorophyll (when this is present) in its 
upper half and reserve starch in the lower half. A cross-section 
_is shown in fig. 64. This set of tissue, therefore, is reproductive 
