206 



THE CELL. 



with Flemming's weak solution, the imclein loses its power of 

 becoming stained, whilst the nucleoli become stained dark red in 



C 



A 







FIG. 99. A Nucleoli, wifch granules, which are dissolving (PI. III., Fig. 4). B Nucleus 

 of a sperm-mother-cell of Escort's megalocepfiala "bivalens from the end of the growth zone. 

 Preserved in Flemming's weak solution of chroino-osmic acid. Stained with acid fuchsine 

 (PI. III., Fig. 6). C Nucleus of a sperm-mother-cell of Ascaris megalocephala livalens 

 from the middle of the division zone. Preserved in Flemming's weak solution of chromo- 

 osmic acid. Stained with acid fuchsine (PI. III., Fig. 9). 



acid fuchsine (Fig. 99 A, B). By this means I was able to observe 

 that during the preparatory stages the nucleolus breaks up into 

 several pieces, that small portions of these dissolve off, and that 

 similar particles, stained a deep red, are deposited upon the nuclear 

 threads. Later on, when the nuclear segments are fully formed, 

 and the nucleolus has quite disappeared (Fig. 99 (7), the centro- 

 somes become visible upon the surface of the nucleus, and more- 

 over, each nuclear segment is seen to enclose a dark red granule, 

 which reacts towards staining solutions like the substance of the 

 nucleolus. 



Several interesting reactions with staining solutions seem to 

 point to the fact that the nucleolar substance is taken up into the 

 nuclear segments, although probably in an extremely finely divided 

 state. As Wendt has discovered by his experiments on plants, 

 the nuclein framework of the nucleus from the embryo sac of any 

 one of several species of the Liliacece is stained blue green when 

 treated with fuchsine iodine-green, whilst the nucleoli are coloured 

 red. On the other hand, during the division stages, when the 

 nucleoli are dissolved, the nuclear segments are stained violet. 

 Further, later on, after the nucleoli have reappeared in the 

 daughter nuclei, the nuclear threads are again stained bluish green. 

 Wendt explains this varying reaction towards staining solutions 

 by assuming that during division the nuclear segments absorb the 

 nucleolar substance, and give it up again after division, so that 

 the nucleoli may be found in the daughter nuclei. 



