Pe rah SE AE by rear dT RS te OR a ede BAL YN a 5 ane Oe fe a ee aoe sah t <a" 
een Pyar ho eel eat, arate 
1896 | CERTAIN PYRENOMYCETOUS FUNGI : 313 
plasm and consequent deep staining. In the earlier stages, when 
the structure consists of two to four cells, faint outlines of nuclei 
can sometimes be seen, and in one or two cases division was sus- 
pected, but no positive statements are warranted regarding the 
nuclei in the perithecium prior to the formation of the ascus. 
As soon as the ascus is differentiated, however, the nucleus 
becomes very distinct. No fusion has been observed, and in the 
youngest stages each ascus contained one large clearly defined 
nucleus. This nucleus is much larger than those found in the 
mycelium, but is otherwise similar. 
That some process of nuclear division takes place is apparent. 
As before stated, the young ascus contains a single nucleus. 
This has been called by De Bary the ‘primary nucleus.” It 
does not, however, as he says, lie always in the end of the ascus. 
Its position is variable, but it is found oftenest near the center 
of the ascus and in a bed of very dense protoplasm. Its diameter 
is often equal to half that of the ascus. Neither does this pri- 
mary nucleus disappear and eight daughter nuclei appear simul- 
taneously, as has been stated. All the successive stages of divi- 
‘ion have not been observed, but an ascus containing two nuclei 
was found, and another with eight. In the latter case they were 
arranged in pairs, the two largest having moved a greater dis- 
tance apart than any other pair (fig. 7g). This, with the fur- 
ther evidence about to be given, was considered sufficient proof 
that the eight nuclei are provided by successive bipartitions 
of the primary nucleus. On this point the ascus next to be 
described was indirectly very instructive (jig. 20). In its pro- 
toplasmic content could be discovered, by careful focusing, the 
Outlines of eight spores. The protoplasm in the spores was more 
dense than that surrounding them, and hence they were stained 
tga The two spores nearest the base of the ascus con- 
“ene nucleus each and were not divided. A third spore 
Seg two nuclei, lying near the ends of the spore, but 2 
eae as wall had yet appeared. Four nests spores i , 
ita cee situated at various distances from ac 
: 1S septum was unstained, appearing like an open 
