284 
G. R. BISBY 
The formation of the cokimella in Stemonitis fusca takes place by 
means of a progressive deposition of wall material along a cylindrical 
space that reaches from the base of the young fructification upward 
through the rising mass of protoplasm. The irregular radiations and 
extensions of the apical part of this space resembles somewhat the 
condition as figured by De Bary ('87) for Stemonitis ferruginea (p. 432, 
figure 186, a) in which the upper portion of the columella is pictured 
as frayed out in a brush-like fashion. The exceedingly vacuolar ap- 
pearance of th^ protoplasm above the columellar space (see figure 16) 
suggests both the rapid pushing up of slender, tubular invaginations 
from the apex of the space itself, as well as the final incorporation 
into the columellar space of the vacuoles that lie in its upward path. 
It has already been pointed out that some protoplasm is regularly 
left within the columellar space, cut off from the mass above the 
columella by the upward pushing, slender invaginations and vacuolar 
cavities which are characteristic of this area apically from the tube. 
In younger stages of columella formation, the protoplasm included in 
its hollow interior shows some evidences of continued activity, although 
often broken up into very small, rounded fragments. In older stages, 
however, its appearance suggests a much less active condition; and it 
probably ultimately dies. 
In Stemonitis the same essential phenomena in regard to capillium 
formation undoubtedly obtain as those described above for Physarella. 
Views of early stages of the spaces in which are to be secreted the 
capillitial threads show an appearance of considerable irregularity 
and anastomosis, and they are with difficulty traced through the foamy 
protoplasm (figure 17).. Later stages show the threads with more or 
less thickening deposited adjacent to the plasma membrane. Ordi- 
narily, careful focusing on thin sections reveals clearly the tubular 
character of these threads. The attachment of capillitial threads to 
the central columella displays a condition somewhat coniparable to 
the attachment to the sporangium wall in the case of Physarella. 
It is noteworthy in Stemonitis that the threads are evidently in con- 
nection with the exterior deposition upon the columella, pointing to 
the fact that the threads are formed by a deposition no different from 
that which forms the columella; nor indeed from the wall deposit 
itself, as figure 21 evidences. The further fact that in the cases figured 
(figures 18 and 19), the lumen of the thread is not continuous with the 
lumen of the hollow columella shows that in these instances at least, 
