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Charles E. Allen 
Chamberlain, 1903); and in spore mother cells of Fegatella (Farmer, 
1895 b), Riccia and Ricciocarpus (Lews, 1906). 
In the divisions in the genninating spores of Pellia, Farmer and 
Reeves (1894) and Strasburger (1895) find the chromatin, much as in 
the divisions I have described, localized in a narrow equatorial band 
within the nucleus at a time wlien the membrane is still intact. Wilson 
(1911) finds essentially the same thing in the androgones and androcyte 
mother cells of Pellia, as does Van Hook in the divisions in the arche- 
goniophore of Marchantia. An apparently similar equatorial aggregation 
is described by Bolleter in the anthcridial cells of Fegatella. Davis’ 
description of a “synapsis” preceding each mitosis in genninating spores 
of Pellia mav possibly refer to the same stage of chromatin aggregation. 
Escoyez (1907), too, observed a central gathering of chromatin in the 
androgonial nuclei of Marchantia, but apparently considerably earlier 
than the occurrence of the aggregation in question in Polytrichum. 
Little information is supplied by published observations regarding 
the time of appearance of the first indications within the nucleus of an 
approaching division, relative to the stage of development of the extra- 
nuclear spindle rudiment. However, to judge from Davis’ figures, the 
poles are defined and the spindle rudiment is well formed in the germinat- 
ing spores of Pellia before the beginning of spirem formation; and one 
figure given by Woodburn (1911) of a stage in the preparation for division 
of an androcyte mother cell of Marchantia indicates tliat the relations in 
these cells are substantially the same in this respect as they are in the 
corresponding cells of Polytrichum. 
I find no mention of a gradual collapse of the nuclear membrane 
such as occurs in Polytrichum, unless Ikeno’s (1903) description, for the 
androgones of Marchantia, of a flattening of the nucleus in the equatorial 
plane just before the membrane disappears, is to be so interpreted. 
The available data concerning nuclear division in brvophytes are 
seen to be very scanty. Still, there appears to be reason for suspecting 
that the course of mitosis may be substantially uniform, even in relatively 
minor points, throughout this group — modified, of course, by special con- 
ditions in particular cells, as for example by the four-lobed form of the 
spore mother cells in the Jungermanniales. 
