Tor] BROW N—LACHNEA SCUTELLATA 2905 
are joined to the centrosomes (fig. 50). The plasma membrane 
around the ascus, which was pulled in where the radiating fibers 
were connected with it; has by this time very nearly resumed its 
normal position against the ascus wall (fig. 50). The nucleus 
which is still connected by fibers to the membrane is, by this 
means, drawn toward the periphery, and this may account for the 
beak and also for the further bending back which has taken place in 
the radiating fibers which were not connected with the membrane. 
Since the fibers seem to exert a pull on both the plasma mem- 
brane and the nucleus, and to be bent as a result of the movement 
of the nucleus, it would seem that they must be relatively solid 
structures. This view is strengthened by their behavior during 
telophase in all three divisions. After the chromosomes have 
reached the poles, the fibers connecting the centrosomes continue 
to grow and become bent as though under tension. At the same 
time beaks are formed on the nuclei at both poles. This may be 
due to the pressure of the connecting fibers, or in part at least to 
a pull exerted by the fibers radiating into the cytoplasm, as in the 
case of the beaks formed on the eight nuclei. 
Harper (19, 21, 22, 23) has described the cutting out of the 
spores in Erysiphe, Lachnea scutellata, Pyronema, and Phyllactinia. 
According to this author, the fibers radiating into the cytoplasm 
fold back and fuse into a membrane which grows back until its 
edges meet at a point opposite the centrosome. FAULL (12) has 
studied spore formation in a number of Ascomycetes, and con- 
cludes that the spores are not cut out by a membrane formed of 
fused astral rays. According to him the spores are delimited by a 
limiting layer of protoplasm. On the site of this there is formed 
a plasma membrane about the spore, and another opposed to it 
lining the cavity in the epiplasm. The formation of these is 
probably preceded by a cleavage of the limiting layer. The 
€xospore is formed between the two opposed plasma membranes. 
OVERTON (31) in Thecotheus pelletieri and FRASER (14) in Humaria 
rutilans describe the spores as delimited by the astral rays. In 
Lachnea, the first sign of the cutting out of the spore is the appear- 
ance of a delicate membrane at the outer limits of the recurved 
astral rays. This usually appears first around the centrosome 
