512 Farmer . — -On Spore- Formation and 
sideration of the events which occur during the reconstruction 
of the daughter-nuclei. But I may at once say that I do not 
believe that the entire nucleolus is concerned in the process. 
For quite apart from the fact that the disappearance of the 
nucleolus does not, by any means, always coincide with the 
growth of the chromosomes, there are chemical considerations 
which render any such hypothesis untenable. 
Zacharias 1 has clearly shown that the chemical constitution 
of the chromosomes, and certainly that of their chromatin 
component, is by no means identical with that of the nucleolus ; 
for whereas the former contains nucleic acid in combination 
with other substances, this is wanting in the nucleolus which 
consists of plastin and albumen. But albumen also forms 
a constituent of chromatin, according to the statements of 
Zacharias and also of Kossel 2 , who regards chromatin as 
containing, besides nucleic acid, a variable quantity of albu- 
men. Zacharias 3 has also pointed out that the male nuclei, 
which are so rich in nuclein, are usually destitute of a nucleo- 
lus, whilst the oosphere nucleus is poor in nuclein, but possesses 
a large nucleolus. The inference to be drawn from this obser- 
vation seems to be, that the nucleolus, though not in itself 
containing chromatin, is able to furnish at least one, and that 
probably the albuminous constituent of this substance, and 
that when the chromatin diminishes, as happens during the final 
stage of karyokinesis, it again decomposes, and that the albu- 
minous matter contributes to the rehabilitation of the nucleolus. 
This would perfectly agree with Kossel’s observation that 
chromatin can be split up into albumen and other substances. 
It seems hardly possible to explain the intimate relations 
which exist between the linin and the nucleolus, during the 
early and latest phases of mitosis in the liverworts, as a merely 
accidental circumstance. Not only their mutual positions, but 
also the relative differences in their staining capacity, all point 
1 Zacharias, Ueber den Nucleolus. Bot. Zeit., 1885; also Ueber d. chemische 
Beschaffenheit v. Cytoplasma u. Zellkern. Ber. d. deutsch. Bot. Gesellsch., 1893. 
2 Kossel, Ueber die Nucleinsaure. Verhandl. d. Berl. Physiol. Gesellsch., 1892. 
3 Zacharias, Ueber Beziehungen d. Zellwachst. z. Beschaffenheit d. Zellkerns. 
Ber. d. deutsch. Bot. Gesellsch., 1894, p. 106. 
