Sands—Spore Formation in Microsphaera Alni. 739 
ruing’s weaker solution diluted one-half with water. Flem¬ 
ming’s weaker solution gave in general the best results, al¬ 
though the younger stages fix well in the diluted solution. 
The material was collected in September and October 1904 
and 1905. Sections were cut 5/x and lOg thick and stained 
with Flemming’s triple stain. 
I shall describe the structure and the development of the as- 
cocarp from the time when the ascogonium is completely en¬ 
veloped by the perithecial hyphae, leaving the earlier stages 
for description later. 
The young ascogonium appears as a relatively large single 
cell, somewhat elongated and curved, surrounded by the first 
hyphal envelop. This stage, in which two nuclei are present, 
is of frequent occurrence. The nuclei lie in the long axis of 
the ascogone and invariably show distinct centers and a single 
nucleole. 
With the triple stain the centers are usually violet or dark 
red, and are easily distinguished from the dark blue chroma¬ 
tin or from the blue gray membrane of the nucleus. The nu¬ 
cleole is always a bright red, the nuclear sap is clear and un¬ 
stained, while the cytoplasm varies from gray to a faint orange 
color. 
The chromatin at this stage often forms a spindle-shaped 
mass between the central body and the red nucleole. Chro¬ 
matic strands cannot be made out, but the chromatin appears 
rather evenly granular, though plainly connected with the 
central body (Fig. 4). 
The ascogone grows both in diameter and length, its nuclei 
divide, and later cell division occurs, so that a multicellular or¬ 
gan is formed consisting of four or five cells. During the 
growth of the ascogone, the envelop becomes more complex, 
one or two layers of cells being formed about the first layer. 
The ascogone, being hemmed in on all sides by its envelop, 
curves and turns about as it grows, apparently expanding in 
whatever direction it finds least resistance, so that a much bent 
structure results. From just what cell or cells the ascogenous 
hyphae arise I have not been able to determine. It appears 
that many ascogenous hyphae bud out at about the same time. 
