49 2 Wager . — On Nuclear Division 
tions upon the structure and division of the nuclei in the basidia 
of Agaricus ( Stropharia ) ster cor arias \ in which I pointed out 
that not only did the nucleus possess a structure closely 
resembling that of the higher plants, but that the nuclear 
division more nearly resembles that of the latter, inasmuch 
as a distinct equatorial plate, and apparently a spindle-figure, 
were produced. 
I have briefly referred to this paper here because Rosen 1 2 
has more recently published a description of some observations 
upon nuclear division among the Basidiomycetes, in species 
other than those I have examined, which do not, if I under- 
stand him rightly, at all agree with mine. It will be useful to 
briefly summarize his results. He observed many different 
species, but as they all agree in their chief details, he confines 
himself mainly to a description of Lepiota (. Armillaria ) 
mucida. 
The young basidia contain two or more nuclei, generally 
arranged in pairs. The mature basidium contains a single 
nucleus. This basidial nucleus arises by the repeated fusion 
of the smaller nuclei originally contained in the basidium — six 
or eight probably. From an examination of Psalliota cam - 
pestris he thinks it possible that the majority of these small 
nuclei may be produced in the basidium. 
The single nucleus of the mature basidium is at first dense, 
and allows only faint indications of a nuclear network to be 
seen, in close proximity to the nucleolus. The nucleus soon 
increases in size, however, and then it is seen that the chromatin 
is restricted to a long coiled and crumpled thread. Soon 
numerous sharp bends appear in it, and finally the thread 
becomes broken up into segments. These segments collect 
at last into two little star-shaped heaps, opposite each other, 
in the wide nuclear cavity ; then, the nucleolus becomes 
dissolved and the nucleus divides into two, without any 
indication of spindle-figure or connecting threads. In each 
1 Loc. cit. 
2 Studien iiber die Kerne und die Membranbildung bei Mynomyceten und 
Pilzen, Cohn’s Beitiage zur Biologie der Pflanzen, Bd. VI. p. 259, 1892. 
