44 Osborn. — Some Observations on Isoetes Drummondii , A.Br. 
About the end of May or early June the first leaves of the new 
vegetative season appear, while previous!}^, below ground, a new set of 
roots has begun to develop upon the stock. Coincidently, or slightly 
before the appearance of the leaves, the bases of the previous season’s 
sporophylls appear at the surface of the soil. These are forced upwards 
during such time as the soil is thoroughly sodden by the expansion of 
a mucilage tissue formed at their bases. In the field it is noticeable that 
the new leaves frequently appear from neat circular holes in the soil, 
rather like large worm-holes, which may contain a clear jelly. These holes 
are drilled by the sporophyll bases in their journey to the surface. In other 
•cases the old sporophyll bases and the laminae of the new leaves appear 
above the surface of the soil at the same time (Fig. 3). 
If rain continues after the projectile-like mass of sporophyll bases 
reaches the surface, it may fall apart, separating the individual sporophylls ; 
but if a period of fine dry weather follows after the mass is exposed, it 
will dry up, forming a hard cone-shaped body (Fig. 4), and in this state 
may be blown or rolled away from the plant producing it. Ultimately 
the mass falls apart and the sporangia open by a tearing away of the walls 
from their attachment to the sporophyll. This only occurs during rain or 
immediately after, when the soil is thoroughly sodden, often showing 
a shimmer of surface water.. 
Observations on the Stock,. 
Apart from its method of spore dispersal the study of Isoetes Drum- 
mondii has proved interesting in that it shows the behaviour of the stock 
of an Isoetes when grown under conditions with a sharp alternation of 
vegetative and resting seasons, conditions that are the reverse of the ‘ even 
growth * implied in the generic name. 
If a plant be dug up and examined during the growing season the 
appearance of the stock is as seen in Fig. 1. The current season’s leaves 
occupy the centre of the upper leaf-bearing surface of the stock. Externally 
to this are the projecting portions of the three lobes, which are composed 
of a series of nested scale-like caps, that usually break away upon the 
removal of the plant or on washing. The caps show no remains of the 
sporophylls that were produced on their leaf-bearing surface ; all that 
remains of the leaves is two or three scales or the rotting bases of the few 
sterile leaves formed first in each season’s growth. 
The sides and lower surface of the stock bear numerous roots (Fig. 5). 
The majority are dead and brown ; only those that arise from the centre of 
each groove are white and functional. 
The structure of the lobe is of interest. It shows clearly the three 
types of surface distinguished by Lang, 1 viz. the leaf-bearing surface the 
1 Lang, W. H. : Mem. and Proc. Manchester Lit. and Phil. Soc., lix. No. 3, p. 9, 1915* 
