Freda M. Bachmann 
414 
in Pyronema (20) and in Boudiera(lS). As to Collema pulposum, my results 
are in agreement with those of Baur (3) and Darbishire (25). I have 
found that tlie several cells of the earpogone next to the hvplia on which 
it is borne do not become perforated, and tliat later these cells brancli 
repeatedly to form the hyphae which terminate in the parapliyses. I 
have found also that the vegetative hyphae in the region surrounding 
the earpogone are stimidated to growth and form a part of the sterile 
tissue of the fruit bodv. 
Stahl (74) has described the disappearance of algal cells in the fruit 
body very much as I have observed it in Collema pulposum. He found 
that as the ascogone becomes ensheathed, Nostoc filaments areincluded, 
but later these disappear. They lose their green color and become yel- 
lowish and later are only small refractive bodies. In my material the 
Nostoc filaments are not numerous in the region of the ascogones so 
that very few become enclosed with the latter in the developing apo- 
thecium. However, as the parapliyses grow upward toward the surface 
and through the zone where Kostoc filaments abound, some few of the 
filaments come to lie among the parapliyses, but later disappear. The 
growth of the developing fruit body seems to be more rapid toward the 
periphery. This results in a depression in the center in which Nostoc 
filaments are very numerous. Bv the time the parapliyses are formed, 
the Xostoc cells have lost their spherical sliape and in stained sections 
do not sliow a differentiated central body but are deeply staining red 
masses. As the apothecium continues to enlarge, these red masses dis- 
appear completely or may be seen for a time as small red disintegrating 
masses. 
The origin and development of the ascus. 
The formation of the ascus I have not observed with certainty. 
Baur (5) has figured it in Anaptychia ciliaris as arising from the pen- 
ultimate cell of an ascogenous hypha, the tip of which is bent downward 
to form the liook that has been so commonly described for a number 
of ascomycetes. In Galactinia succosa, Maire (62) found that there 
may be three successive svnkaryons with no trace of a liook, the end 
cell becoming an ascus. In Acetdbula acetdbulum he (68) found that a 
liook is formed; this is not transformed into an ascus, but gives rise to 
two, three, or four binueleate cells of which the last is the ascus. In 
this suceession of binueleate cells Maire sees a similarity to the long 
series of binueleate cells in the basidiomycetes. In Acetdbula tliis series 
tends to be longer than in most otlier ascomycetes. Guilliermond (44) 
