Igtt] CURRENT LITERATURE 325 
Germination of fern spores in darkness.—It has been almost the universal 
experience of those who have investigated the germination of fern spores that 
at usual room temperature and with so-called inorganic nutrition they will not 
germinate in complete absence of light. However, at high temperature, or 
in sugar or peptone solutions, germination in total darkness has been induced. 
ISCHER® has now found that the spores of one of the commonest and most 
widely distributed ferns, Polypodium vulgare, are able to germinate in dark- 
ness at 25° just as well as in light. This is probably the best case on record 
for germination in darkness, since prothallia were actually obtained, and 
not merely a bursting of the exospore, as LAAGE reported for Osmunda regalis 
and other ferns. The prothallia formed in darkness differ somewhat from 
those of the same age produced in light, being composed of more and longer 
cells. It is probable that some limiting factor prevents the germination of 
the spores of most ferns in darkness; and discovery of the proper conditions 
for germination may show that the spores of many species are capable of devel- 
oping prothallia without light.—CHartes A. SHULL. 
Vegetation of Nockamixon Rocks and Navesink Highlands.—It is im- 
portant to have on record the natural vegetation of areas that are becoming 
densely populated, since tracts that have escaped the modifying influence of the 
ax and the plow are being reduced to a minimum. HARSHBERGER has con- 
tributed much to this record, and has lately investigated” the plant formations 
on a series of cliffs, known as-the Nockamixon Rocks, on the Delaware River 
in Pennsylvania. Upon the talus a climax mesophytic forest has developed, 
characterized by the beech, maple, and associated forms, with an oak forest 
upon the crest of the cliffs and a mixed one upon the larger rock shelves. 
More recently he has studied the Navesink Highlands upon the coastal 
Plain of New Jersey. The forest is here dominated by the chestnut and the 
chestnut oak, with a more xerophytic association at the summit, character- 
ized by dwarfed trees placed at wide intervals —Gro. D. FULLER. 
sng Sig in Scottish peat mosses.—Lewis has published a fourth 
Paper* upon this subject, the present investigation dealing with the Scottish 
Highlands and Shetland. An appendix also discusses the Icelandic peat 
deposits. His former conclusions as to the principal stages in the history of 
vegetation over peat-covered areas, since the later stages of the glacial period, 
were oe oeaantly confirmed. The stages are as follows: (1) an arctic-alpine 
9 FISCHER, sar sae und Dunkelkeimung bei Farnsporen. Beihefte Bot. 
Centralbl. 27°26 
* HARSHBERGER, peas W., The plant — of the Nockamixon Rocks, 
Pennsylvania. Bull. Torr. Bot. Club 36:651-6 
, The: vegetation of the Navesink abs Torreya 10:1-10. Igio. 
* Lewis, Francis J., The plant remains in the Scottish peat mosses. Part IV. 
Trans. Roy. Soc. Edinburgh 4737937833. pls. 5. 1911. 
