50 Wisconsin Academy of Sciences, Arts, and Letters. 
stipe. At the top of the stipe they spread out in every direction 
to form the pileus and gills. The cells are regularly binucleated 
and are filled with very dense cytoplasm. 
Certicium lilacino-fuscum was also studied. It appeared in 
great abundance on a damp log in the green-house. Portions a 
quarter of an inch square were removed with a thick layer of the 
substratum and fixed in Flemming’s weaker solution. 
The surface layer is formed of densely packed short celled 
hyphae which grow perpendicularly to the substratum. The 
hyphae branch repeatedly, the branches crowding in between the 
hyphae. The cells are long and slender and so closely crowded 
together that I could make out the contents in only a few cases. 
In favorable preparations in a few instances cells were seen with 
two nuclei near the center and the remainder of the cell was 
filled with very granular cytoplasm. The clamp connections be¬ 
tween adjacent cells are nearly always present. On the lower 
surface there are a large number of thick walled hyphae, desti¬ 
tute of cytoplasm, which form a loose felted layer and then 
penetrate the wood for some distance. They probably serve as 
a protective layer and also hold the mat close to the substratum. 
Among these basal thick walled hyphae there are others with thin 
walls and protoplasmic contents which also penetrate the wood 
in every direction and are usually single but occasionally are 
found in masses filling a vascular element of the wood. They 
are formed of long slender ceils with two nuclei. 
Rhizomorphs. 
In many Agarics the hyphae form mycelial strands which 
often grovr to great length. These strands may branch fre¬ 
quently but without regularity and resemble roots. In some 
species the branches anastromose frequently forming a loose net¬ 
work; a character which is especially pronounced in DictyopJiora 
duplicata. The structure of these so-called rhizomorphs is best 
known through the descriptions of Armillaria mellea by De 
Bary, Goff art and others. The forms wdiich I have studied show 
a much simpler structure but they apparently have the same 
origin, the same general character of growth and doubtless serve 
the same general function. They provide a storage for reserve 
