PTERIDOPH YTES—L Y COPODI ALES 
247 
other, by Mr. 0. Degener, adds four more stations in Massachusetts 
and mentions the finding of prothallia near the crater of Kilauea, 
Hawaii. Both papers appeared in the Botanical Gazette of March, 
1924. With these papers describing the finding of prothallia, it is 
probable that prothallia of Lycopodium, especially the older prothallia 
with sporelings attached, will become familiar objects in botanical 
laboratories. 
Once found, the technic is easy. Fix in the special chromo-acetic- 
osmic-acid solution, or this with the acetic reduced to 2 or even to 
1 c.c. Stain in iron-alum haematoxylin and orange for the develop¬ 
ment of archegonia and antheridia. Use safranin, gentian-violet, 
orange for the development of the embryo. For the endophytic 
fungus which stains well with the last-named combination, try the 
method of differentiation of pathogen and host, described at the close 
of the chapter on fungi. 
The prothallia of Lycopodium inundatum , the only species in the 
United States known to have aerial green prothallia, have not yet 
been discovered in this country, although they have been found in 
Europe. 
It would seem natural to get the prothallia by germinating the 
spores, but here again no one has had any notable success, except 
Bruchmann. In some species, the spores do not germinate for several 
years, but when the prothallia are once developed they continue to 
bear archegonia and antheridia for several years. The spores of 
L. Selago germinate in 3 to 5 years after shedding; those of L. clavatum 
and L. annotinum in 6 to 7 years. In L. clavatum and L. annotinum 
archegonia and antheridia develop in 12 to 15 years after the spores 
are shed. L. inundatum germinates more promptly—in 10 days to 
6 months—but no one has succeeded in keeping a culture up to the 
archegonium stage. 
Botanists in Lycopodium localities should look for prothallia. 
Since the subterranean forms are perennial and as large as a grain of 
wheat, some reaching a length of 1.5 cm., it would seem as if they 
should be found wherever Lycopodium grows. 
Selaginella.—-Material of Selaginella, in all phases of the life- 
history, is easy to secure, but not so easy to handle after it is obtained. 
As many as 340 species, mostly tropical, have been described, only 
3 of which are common in the range of Gray’s Manual. Of these 3, 
Selaginella apus is best for sections. It is found in moist or wet 
