291 
of Lycopodmm clavatum , L. 
older plants than that represented in Fig. 1. Its position 
with regard to the main axis of the plant is variable. The 
differences probably depend on the inclination of the surface 
of the prothallus upon which the plant was borne, the young 
shoot and root of course tending to grow vertically upwards 
and downwards respectively. Figs. 29 and 30 represent two 
extreme examples. In the former the position of the foot is 
distinctly lateral, the surface of the prothallus having in all 
probability been almost vertical ; while in the specimen 
represented in Fig. 30, which was probably inserted on a 
horizontal surface, the foot is in the same line as the axis of 
the shoot, the root arising at the base of the latter. For 
a variable distance above the position of attachment to the 
prothallus, the stem bears only small colourless scale-leaves 
which higher up pass by gradual transitions into ordinary 
green foliage-leaves (Fig. 1). This doubtless depends on the 
thickness of soil and moss through which the shoot had to 
grow before reaching the light. 
The Endophytic Fungus. 
It has been mentioned above in the general description of 
the prothallus that its lower half harbours an endophytic 
Fungus, the distribution of which within the cells of the layers 
marked b and c and between those of the layer above (d) was 
described. It will be sufficient in this place to refer to Fig. 6, 
with regard to which it should, however, be noted that the 
intercellular mycelium is more uniformly distributed than was 
demonstrable in the portion of the section drawn. When 
thicker sections are mounted in Schulze’s solution, the fila- 
ments of the Fungus swell somewhat and take on a purplish 
colour ; it is then seen that the mycelium is present throughout 
the entire thickness of the storage-layer. 
The cells containing the Fungus, although their proto- 
plasmic body was occupied by closely packed hyphae, appeared 
to be perfectly healthy. The nucleus presented a normal 
appearance (Fig. 32), though occasionally it may be altered in 
