1922] SPESSARD—LYCOPODIUM 307 
most abundantly. It is difficult to describe what this is. In 
general one must follow the same principles involved while search- 
ing for the prothallia of any pteridophyte group. 
For the prothallia of L. Jucidulum, moisture is without doubt 
the most important factor. Countless millions of spores shed 
annually from an acre of these plants fail to produce prothallia, 
either because they are washed away into streams, driven too deeply 
into the soil, lodged in water logged depressions, or are subjected 
to dry conditions before and after germination. It is only when 
they fall upon a region whose sandy substratum is covered by a 
thin layer of leafmold, and is sufficiently protected from the seasonal 
drought and from inundation, that they germinate and produce 
prothallia. Such a place is a hillside or a hilltop with scattered 
trees, very little shrubbery, and a scattered representation of such 
herbs as the squawberry, wild sarsaparilla, Clintonia borealis, and 
Polygala. Very often grasses and Polytrichum are found in such 
a habitat. A sandy knoll with sparse vegetation and with a swamp 
at its base is an excellent locality. 
BRUCHMANN found many of his prothallia of L. Selago, a related 
Species, in mats of moss. The writer found very few in such places. 
The rich patches just described lay on a sandy hillside and were 
protected only by the leaves which fell the previous autumn. The 
soil was a rich humus for a depth of 1 cm., with almost pure sand 
beneath. Although hundreds of sporelings were found, many 
were in a desiccated condition, and only a very few would ever 
have become adults, for adult plants habitually occur in regions 
a little more moist than where the prothallia and sporelings were 
found. 
Because the prothallia of this species of Lycopodium were found 
growing in such a variety of places, the following list of these may 
be valuable: (1) in a hole at the base of a living birch tree; (2) 
among the decayed needles of Pinus resinosa; (3) under a hard 
maple tree; (4) on the top of a rotten stump; (5) on partly shaded 
hillsides; (6) in the sand under a patch of Polytrichum and Polygala; 
(7) in sand scarcely covered at all with humus; (8) in moldy humus 
(most abundantly); (9) in muck, at the edge of a permanent pond; 
(10) in the wheel tracks of an abandoned forest road. 
