652 Fault .— The Cytology of the Laboulbeniales . 
which is subsequently cut off as the inferior supporting cell, the other to the 
upper end. The nucleus of the trichophoric cell now moves down next to 
the carpogenic cell, and divides mitotically. The membrane separating the 
two cells at this time disappears. One daughter of the trichophoric nucleus 
next moves back to the earlier position occupied by the mother nucleus, 
and is later cut off by a septum ; the other remains with the upper nucleus 
of the carpogenic cell. This pair now undergo division. A transverse parti¬ 
tion then cuts the carpogonium into a binucleate superior supporting cell 
and a binucleate ascogonium. Presumably the nuclei in the ascogonium 
again divide, to supply a binucleate secondary inferior supporting cell which 
is cut off from the lower end of the ascogonium. I cannot speak with cer¬ 
tainty of the nucleation of the supporting cells in all instances. There may 
be variations such as have been found to be the case in the cells adjoining 
the ascogenic cells in many other Ascomycetes. The binucleate ascogonium 
now usually divides by a nearly vertical wall into a pair of binucleate asco¬ 
genic cells, but may at once, without dividing, begin to bud off asci. 
The Ascus. 
The two nuclei of an ascogenic cell divide simultaneously and mitoti¬ 
cally at the advent of each ascus. A daughter of each passes into the young 
ascus, where they fuse. The definitive or fusion nucleus of the ascus now 
enters on a long period of growth, and finally attains a large size. Eventually 
it undergoes three successive mitoses. The first exhibits clearly the pheno¬ 
mena said to be characteristic of meiosis, except that neither here nor in 
the two subsequent divisions is there any change in the number of chromo¬ 
somes. The central body is present and lies outside the nuclear membrane. 
In the prophases of mitosis its relation to the chromosomes is very evident. 
The second division follows rapidly on the first, but the third takes place 
more leisurely. 
Directly after the third division spore formation begins, which differs 
in no respect from the method characteristic of sac fungi. The astral 
rays are thin, long, and quite conspicuous, and are to be seen within the 
spore for some time after its delimitation. They do not unite to form 
the protoplasmic membrane bounding the young spore, and, apparently 
unmodified, have been observed in some cases twisted about the long 
neck of the nucleus while the central body of the latter was still in con¬ 
nexion with the spore membrane. The cavities in which the spores lie are 
also lined by what appears to be a protoplasmic membrane. The spores of 
all the forms examined, with the exception of Amorphomyces , as already 
noted, become two-celled. 
Four spores only are formed, four nuclei of the last division passing to 
the apex of the ascus, where they function no further, and finally disin¬ 
tegrate. The functional nuclei, in Laboulbenia chaetophora at least, are the 
