44 Wisconsin Academy of Sciences, Arts, and Letters. 
of the main hypha have from one to three small nuclei. The 
lateral branch does not show any of the constrictions found in 
the main hypha. It is very difficult to locate the cross walls 
since when newly formed they are extremely delicate and easily 
confused with a strand of cytoplasm. In one of the cells there 
are fourteen very small nuclei many of which are only slightly 
larger than the nucleole of the large nuclei in the main hypha. 
They have a nuclear membrane, a minute nucleole and a few 
scattered granules of chromatin. The other cells of the branch 
have one or two large nuclei. 
At the end of twenty-four hours a well developed mycelium is 
formed. Fig. 11 is drawn from a mycelium that was formed in 
a hanging drop culture in twenty-four hours. In addition to 
the main hypha and the lateral branch mentioned in the pre¬ 
vious description a second smaller branch is formed close to the 
spore. These hyphae branch repeatedly, without any regularity. 
The original hyphae are larger and straighter than any of the 
lateral branches and for convenience in distinguishing them I 
shall call them the primary hyphae. In them the cells are very 
unequal in length but the majority are from seven to eleven times 
as long as they are broad. The number of nuclei varies also. 
The cell next to the spore contains a very large nucleus in the 
center and a small one lying at one side near the junction of one 
of the branches. The next few (five or six) cells of each of the 
primary hyphae have three or four nuclei which are slightly 
smaller than the one found in the first cell. The nuclei are usu¬ 
ally near together at the center of the cell but in one or two in¬ 
stances one of them is slightly separated from the others. The 
next cells for some distance (eight or nine cells) have two nuclei 
which may be close together or separated. In the remainder of 
the hyphae the nuclei are separated at some distance from each 
other but in many cases it is impossible to distinguish a cross 
wall between them. 
The lateral branches are much smaller and more irregular 
than the primary hyphae and the cells are shorter, three or five 
times as long as they are wide, and usually contain a single 
nucleus although cells containing four or five are frequently 
found. In a few instances where the branches extend to the 
