228 BOTANICAL GAZETTE [MARCH 
Davis and of the reviewer are frequently discussed through the work. In the 
opinion of the reviewer, our technique was also good and enabled us to see the 
structures described in the present paper, so that differences in conclusions are 
due in large measure to differences in interpretation of structures which other 
investigators have seen. The present writers support the reviewer’s conclusions 
that the two poles of the chromatic figure arise in succession and independently, 
and also that the nuclear membrane belongs to the category of the H autschicht. 
Without details, some of the principal conclusions are the following: In the 
segmentation of the spore (beginning with the third mitosis) the asters are con- 
tinuous from pole to pole and the achromatic figure surrounds both the nucleus 
and the “‘polar vesicles” (‘‘caps’’). The achromatic figure results simply from 
a rearrangement of the general cytoplasmic reticulum. Neither the nucleus nor 
the vesicles (caps) contribute to the formation of the spindle. The vesicles are 
nothing but nuclear sap diffused into the cytoplasm. After mitosis the achro- 
matic structures are transformed into the general cytoplasm of the cell. At no 
stage is there a genuine centrosphere or centrosome. The first mitoses in the 
germinating spore and the mitoses in the spore mother-cell show neither asters 
nor polar vesicles (caps), but in other respects the evolution of the achromatic 
figure is the same as in other mitoses. The authors hold that there is no distinc’ 
tion between kinoplasm and trophoplasm. No importance is attached to the 
structure described by others as a centrosphere. These researches on Pellia 
contradict many theories in regard to the mechanism of mitosis—C. J. CHAM- 
BERLAIN. 
PHILLPs's has contsibuted some ‘Startling discoveries to an already confused 
subject. Particularl t to the structure of the cen- 
tral body of the Cyanophyceae, which he regards as a nucleus, and the occur- 
rence of sexual fusions in the formation of the spores. In unsectioned filaments, 
since “‘sections revealed very little that could not be seen equally as well in the 
uncut object,” the author has discovered that the chromatin of the central body 
is aggregated in hollow vesicles in the resting cell. ‘This vesicular appearance 
disappears in the dividing cell and the chromatin granules become arrange 
loose network. In this condition, he finds the minute granules themselves multi- 
plying by transverse division. Nuclear division follows, which may be by one of 
two modes, both occurring even in the same species. One, according to the 
author, evidently corresponds to a direct division, while the other is 4 primitive 
mode of karyokinesis. The latter resembles closely the method of mitosis 
13 PHILLips, O. P., A comparative study of the cytology and movements : cpa 
phyceae. Contrib. Bot. Lab. Univ. Pennsylvania 2:237-335- pls. 23-25- 19° 
14 Kout, F. G., Ueber die Organisation und Physiologie der Cyanophyce 
und die mitotische Theilung ihres Kernes 
at 
