ECOLOGICAL ADAPTATIONS OF CERTAIN FERN PROTHALLIA 485 
This is the official record for the U. S. Weather Bureau station at 
Bloomington, Ind., and the figures show the readings of standard 
sheltered instruments. When placed in direct sunlight without reflect- 
ing surfaces and in freely moving air, the instruments showed a maxi- 
mum of 544° C. These conditions were disastrous for many forms 
of vegetation. Midsummer and late annuals were killed outright. 
Ferns, except the early fruiting species or those growing in most 
favorable localities, failed to mature spores. Even the hardier soil- 
growing mosses showed remarkable mortality. 
Camptosorus patches were visited in October and December, IQI^,- 
and in early March and April, 19 14. In more exposed places, on* 
limestone ledges, but few spores were matured in 19 13, and most of 
the sporophytes suffered, some being killed by the dry summer. No 
prothallia were found in these places up to April, 19 14, although they 
may usually be found in the autumn. On April 16, careful search 
was made in a wide wooded ravine where Camptosorus is abundant on 
large blocks and fragments of limestone which are matted with 
mosses, especially Anomodon attenuatus and Brachythecium oxycladon. 
Because of the numerous springs in this ravine, the drought was not as 
severe as in more exposed locations. Almost a full crop of spores had 
been produced in 1913, and on the date given, a few prothallia were 
found on soil in pockets protected by the mat of moss. Some of these 
prothallia showed sporophytes. A few were quite large and showed 
marginal outgrowths like those found on old prothallia of cultures, to 
be described later. Of course all these prothallia must have survived 
the winter, as might be expected with the protection of such a location. 
The largest plants were very much like those of sixteen months old 
greenhouse cultures, and very probably had endured the tempered 
drought of the summer of 19 13. Fronds collected at this place on 
March 31 have furnished an abundance of readily germinating spores. 
Usually prothallia are easily found about colonies of Camptosorus 
from late August to cold weather, and again after April, although they 
do not survive winter in exposed situations in this region. It would 
be of great interest to the writer to know how far north they have 
been found regularly surviving the winter. 
Proliferation or branching of fern prothallia is by no means un- 
known. Some forms produce normally a branched protonema-like 
form. Some have been described as producing hair-like outgrowths 
from marginal cells under conditions of special stimulus. Other forms 
