505 
in the Hymenomycetes. 
dissolved nucleolar substance at some period during the divi- 
sion, and carry it over into the daughter-nuclei, to be given up 
again later as the nucleoli of the latter. 
In those cases where a celh plate is formed, and where 
a portion of the nucleolar substance is, according to Stras- 
burger, to be regarded as going to nourish it and to help in its 
formation, the superabundant nucleolar substance only would 
be taken up in this way. And this would probably not take 
place until a somewhat late stage in the division. 
Strasburger’s 1 observation that the nuclear threads in the 
stage of metaphase are always cyanophil, and that they only 
become erythrophil during the anaphase supports this view, 
although he regards the erythrophil character of the threads 
as due to their nutrition by the cytoplasm. According to this 
observer, as the daughter-nuclei pass through the various 
stages of the anaphase, large quantities of nutrient material 
are taken up into the nucleus, and the latter then gives the 
erythrophil reaction. 
In the division of the nucleus in the basidium of the Hyme- 
nomycetes, where no cell-plate is formed and where no necessity 
exists, therefore, for the accumulation of the nutrient material 
in the equatorial plane of the nucleus, a part of the nucleolar 
substance would probably be taken up at once into the nuclear 
threads, and by means of them be transferred to the daughter- 
nuclei. 
This conclusion appears to me to be more in accord with 
the facts observed. But a certain quantity of’the dissolved 
nucleolar substance probably escapes into the cytoplasm when 
the nuclear membrane disappears, and this would be taken up 
at a later stage into the daughter-nuclei, as is shown by the 
increase in size of the nucleoli, and by the decrease in the 
capacity of the protoplasm for taking up stains. 
In a recent paper, Zacharias 2 brings forward numerous 
observations to show that the strongly-marked cyanophil 
reaction of the nuclear thread is due to nuclein. Rosen 3 has 
1 Ueber das Verhalten des Pollens, &c., Histologische Beitrage, Heft iv, 1892, 
p. 38. 2 Loc. cit. 3 Loc. cit. 
