No. 2.] COMPARATIVE CYTOLOGICAL STUDIES. 
379 
dieselben der Kernsaft wieder zu farben beginnt.” He con¬ 
cludes that the nucleoli are not immediately taken up into the 
chromatic thread, but dissolve in the caryolymph; “ auch ist 
hiermit wohl sicher der Nachweis gegeben, dass sie nicht iden- 
tisch mit den Mikrosomen sein konnen.” The nucleoli arise 
in the meshes of the chromatin network. Strasburger agrees 
with Flemming that they represent a substance distinct from 
the chromatin and nuclear sap, but does not consider it to be 
a living substance, but rather a reserve stuff. 
Guignard (’ 85 ) investigated nuclear division in several species 
of plants. Lilium , young embryo sac: the nucleus usually 
contains a single nucleolus, which is very large, finely granular 
in structure, and situated excentrically between the strands of 
the chromatin network; with the double stain, methylen green 
and fuchsine, it stains red, while the chromatin stains green. 
At the time of the longitudinal division of the chromatin 
filament, the nucleolus commences to stain less intensely, 
vacuoles arise in it, and it finally fragments into small pieces 
which subsequently disappear; the fine granules appearing in 
the nuclear sap at this time are not derivatives of the nucleolus, 
but originate from the cytoplasm when the nuclear membrane 
vanishes. “ Dans le Lilium . . . rien ne fournit la preuve d’un 
apport direct effectue dans la formation du fuseau par le nucleole, 
dont la substance se dissout dans le sue nucl^olaire, pour 
s’incorporer et se melanger, . . . aux autres dements figures 
qui contiennent la chromatine.” In each daughter-nucleolus 
there are several nucleoli of unequal size; these disappear also 
in the subsequent mitosis. Clematis , embryo sac: the nucleoli 
in karyokinesis gradually decrease in size, and it seems “ comme 
si la plus grande partie de leur substance etait absorbee par les 
segments [chromatiques].” Northoscordum: here there are 
several large nucleoli which disappear when the spindle is 
produced, their substance being possibly incorporated in the 
chromosomes. In the metaphasic spirem they reappear in 
contact with the chromatin : “ leur aspect general fait supposer 
qu’ils naissent la ou on les aper$oit dans les jeunes noyaux . . . 
il est a croire que les nucleoles tirent une partie de leur 
substance, tout ou moins, du filament nucleaire auparavant 
