Fertilization in Collema . 
749 
weaken the evidence. Stahl notes that Collema pulposum is frequently 
entirely sterile, though well provided with trichogynes. In these cases sper- 
mogonia were lacking or were represented only by a few small rudiments 
embedded in the thallus. Whether such cases indicate an approach in the 
European forms of C. pulposum to the conditions which I shall describe 
below for the Wisconsin material is an interesting question. 
Stahl’s work on the Collemaceae was later confirmed by Sturgis and 
Baur. Sturgis (31) noted the presence of spermogonia in some species which 
he investigated, and very briefly and incompletely described the spermatia 
and the origin of the spermogonia. In Collema chalazanum , Ach., C. pul- 
posum, Ach., C. nigrescens , (Huds.) Ach., and Leptogium myochorum, Tuck., 
he found the ascogones, trichogynes, and spermogonia exactly as described 
by Stahl. Baur’s (4) results on Collema crispum are likewise in agreement 
with Stahl’s. Stahl’s observations have also been confirmed wholly or in 
part for a number of Lichens other than the gelatinous types in the work of 
Lindau (26), Baur (5 and 6), and Darbishire (10). Spermatia have not been 
found in all Lichens. Fiinfstuck (16) concludes that the genera Peltigera 
and Peltidea have no spermatia, and he described a vegetative origin of 
the apothecia in Peltigera malacea , P. canina , Peltidea apthosa, and P . 
venosa. 
In all Lichens in which spermatia have been found up to the present 
time these cells are borne near the surface of the thallus in large numbers 
in cup-like depressions, the spermogonia, as described by Tulasne in 1850. 
The trichogynes, wherever they have been found, grow up to the surface of 
the thallus, protrude a short distance, and there fuse with the spermatia 
which are brought to them probably by rain as suggested by Stahl. In the 
Collema which I have studied I find no superficial spermogonia. 
My material was obtained from a sandstone cliff overlooking Lake 
Mendota and from the bluffs along the Wisconsin River near Lone Rock, 
Wise. The lichen has also been collected at Blue Mounds, Wise. There 
has always been plenty of material for fixing and sectioning, but never an 
abundance for herbarium specimens. Only small amounts collected at 
different times have been preserved dry. Preissia , Conocephalus, Marchantia , 
Mosses, and a few small flowering plants, mostly in the sunnier places, are 
found in the same habitats. The Collema material grows in the more 
shaded parts or where it is partly shaded by flowering plants. Growth of 
the thalli is interrupted only in the winter and during very dry weather in 
summer. In the spring, as soon as the snow melts and the ground is 
thawed, the thalli resume growth. 
Prof. Farlow has very kindly examined my material and finds that it 
agrees very well with Tuckerman specimens of Collema pulposum , (Bernh.) 
Ach., noting, however, that it approaches C. tenax , (Sw.) Ach. In view 
of the new results which I have obtained and which are unlike anything 
