294 Marquette, Manifestations of polarity in plant cells whicli usw. 
equal distances from eacli otlier. Nägeli 1 ) in 1844 confirmed tliese 
observations. Bot.li Von Mo hl and Nägeli show fibers in their figur.es 
which represent spindle or connecting-fibers, neither of them, 
howewer, recognized their significance for nuclear or cell diyision. 
Strasburger, 2 ) in 1880, for the first time described nuclear diyision 
in the spore-mother-cells of Anthoceros and he ascertained that 
the first karyokinetic figure is so oriented that each of the spindle- 
poles lies midway between two chromatophores, nuclear diyision 
not commencing until the chromatophore has diyided twice in 
snccession and the four daughter chromatophores haye taken their 
Position about the nucleus. He does not directly describe the 
Position of the spindles of the second division but judging from his 
Statements regarding the positions of the four tertiary nuclei it is 
to be concluded that the poles of the second spindles are directed 
each upon one of the four chromatophores. As far as the chroma¬ 
tophores themselves are concerned Strasburger's Observation confirm 
the earlier accounts of Von Mohl and Nägeli. Strasburger also 
describes the connecting fibers in the spore-mother-cells of Antho- 
ceros as extending between the chloroplasts, not between the 
nuclei, and points out that tkis is an exceptional occurrence. Dayis 3 ) 
in 1899 published a paper on the spore-mother-cells of Anthoceros 
in which, however, he does not materially extend the observations 
of the earlier workers as far as the chromatophores are concerned, 
neither does he mention having observed any relation between 
the position of the spindle and the position of tlie chromatophores. 
Van Hook 4 ) also made some observations on cell diyision in Antho¬ 
ceros He gives an interesting figure 5 ) of a cell-plate stage showing 
numerous connecting fibers passing around the relatively small 
nucleus on all sides and centered upon the chloroplasts. Van Hook 
does not enter into a description of spindle formation and nuclear 
division. 
The macrospore mother cells of various Isoetes species show 
conditions which resemble those in the spore mother cells of 
Anthoceros. T schis tiakoff, 6 ) and Strasburger 7 8 ) were the 
first to call attention to the structure of these cells and they were 
later more fully investigated by Fitting. s ) Fitting found a dark 
mass consisting of starch grains and coarsely granulär plasm hing 
against one side of the still undivided nucleus of the macrospore- 
9 Nägeli, C.: Zellkerne, Zellbildung und Zellwaclistum bei den Pflanzen. 
(Ztschft. f. wiss. Bot. Bd. I. 1844. p 49.) 
2 ) Strasburger, E: Zellbildung und Zellteilung. 3. Aufl. Jena 1880. 
3 ) Davis. B. M: The spore mother cell of Anthoceros. (Bot. Gaz. Yol. 
XXVIII. 1899. p. 89.) 
4 ) V r an Hook, J. M.: Notes on the division of the cell and nucleus in 
liverworts. (Bot Gaz. Vol. XXX. 1900. p. 394.) 
5 ) 1. c. PI. XXIII. Fig. 13. 
6 ) Tschistiakoff. J.: Beiträge zur Physiologie der Pflanzenzelle. (Bot. 
Ztg. Bd. 33. 1875. p. 1.) 
7 ) 1. c. 
8 ) Fitting. H.: Bau- und Entwickelungsgeschichte der Makrosporen von 
Isoetes und Selaginella und ihre Bedeutung usw. (Bot. Ztg. Bd. 58. 1900. p. 107.) 
