CYTOLOGY OF EOCRONARTIUM MUSCICOLA 
399 
collected at all seasons of the year. Portions of the main axes of the 
gametophores and their branches as well as pieces of the procumbent 
"stolon" fvere removed from the plant and placed in fixing solution. 
Material was selected from the newer light green branches and from 
the dark green parts developed the previous year, A careful exami- 
nation of an infected individual shows that the hyphae are present in 
both the new and old growths. Healthy host plants were also col- 
lected, and portions of these were used for comparison. 
The most satisfactory fixing agent used was the medium strength 
solution of chromo-acetic acid recommended by Chamberlain (6). It 
gave wholly satisfactory fixation, while solutions containing osmic 
acid proved less useful. Air was removed from the material by means 
of a suction pump. This is particularly necessary when pieces of the 
host plant are treated, since the branches of the gametophore are 
sheathed by small imbricated leaves, and the stolons are covered with 
numerous closely matted rhizoids. The majority of the sections were 
cut 5At in thickness; none exceeded 7^1. They were for the most part 
cut parallel to the long axis of the sporophore or gametophoric branch, 
few transverse sections being made. 
Various combinations of stains were used. Heidenhain's iron 
alum-haematoxylin was given a thorough trial but proved unsatis- 
factory. It was used alone and in combination with certain other 
stains such as Congo red, fuchsin, and erythrosin. Small cytoplasmic 
granules stain deeply with haematoxylin, and obscure the details of the 
nuclear structure. The triple stain of Flemming gave better results. 
After a few trials it became evident that in the study of Eocronartium 
muscicola the use of the shortened method recommended by Harper 
and others is far superior to the longer schedules previously employed. 
A sharper differentiation of the chromatin and achromatic structures, 
fibers, centrosomes, and nucleoli is obtained. This fact combined 
with the economy of time resulting from its use makes the shorter 
method much more advantageous. The three stains in the combi- 
nation were applied for various periods of time, the following schedule 
proving most satisfactory: safranin i minute, gentian violet 5-15 
minutes, orange G 10-20 seconds. 
The nuclei in the various structures of the fungus seem to possess 
an almost equal affinity for the stains, while the cytoplasm in the 
basidia, spores, and hyphae is affected relatively little. The cyto- 
plasm of the host cells stains slowly and does not obscure the hyphae 
appreciably, but the host nuclei stain sharply and rapidly. 
