Marquette, Manifestations of polarity in plant cells which usw. ^>95 
mother-cell. Kays which extend almost to the cell periphery center 
upon tliis mass which elongates and linally constricts in the middle. 
The daughter masses separate front each other until they lie almost 
at the foci of the ellipsoidal mother cell. Arrived liere they once 
more elongate, this time in two planes at right angles to each 
other and to the plane of the first elongation. Constriction in the 
middle again follows this elongation so that the mother cell now 
contains four such masses arranged in the form of a tetrahedron 
about the nucleus and surrounded on all sides by protoplasmic rays. 
Now the nucleus begins to divide. Although Fitting’s material 
did not suffice for a detailed study of mitosis, he made the impor¬ 
tant Observation that the poles of the first spindle lie respectively 
in the middle between two of the starch masses, apparently between 
two sister masses. The spindles of the second division are perpen- 
dicular to each other, the poles lie close beside one each of the 
four starch masses but they never end directly in a starch mass, 
always lying a iittle to one side of them and entirely free in the 
cytoplasm. Fitting also briefly indicates the theoretical interest 
of the described observations without going further, however, than 
to point out that in certain cases even amongst the Archegoniates 
cell division may be initiated by a division of the cytoplasm and 
the included reserve materials; and that the conditons as they are 
found in the macrospore-mother-cells of Isoetes deserve to be 
taken into account by the students of cell-mechanics. Fitting 
worked witli preference on living material, which has its undeniable 
advantage, at the sanie time it is to be hoped that microtome 
sections prepared after successful fixation (which here meets with 
considerable difficulties) will show an abundance of additional 
important details. 
The behavior of the chloroplasts in Coleochaete is also of 
interest. According to Oltmanns 1 ) there is a single chloroplast 
lying at the basal end of the unfertilized oosphere. After the 
entrance of the male cell (which does not contain a cliloroplast) 
the cliloroplast divides, the halves taking position at opposite sides 
of the fusing sex nuclei. The division of the cliloroplast is twice 
repeated so that finally there are eight of them in the oospore. 
Now nuclear division begins; usually there are three successive 
divisions of the nucleus resulting in the formation of eight nuclei. 
Cell division follows, ’ producing eight carpospores, each of which 
contains one nucleus and one cliloroplast. Aside from the fact 
that cell division occurs so thak finally each carpospore contains 
one cliloroplast there are no Statements as to the relations between 
the chloroplasts and the karyokinetic figures. In liis figure 7 
Oltmanns shows two cells, apparently belonging to an antheridial 
brauch, whose nuclei are in the equatorial plate Stage. A chloro- 
plast lies opposite each spindle pole; however, from this fact 
alone it is not possible to conclude much regarding the relations 
q Oltmanns, Fr.: Die Entwickelung der Sexualorgane bei Coleocliaete 
pulvinata. (Flora Bd. 85. 1898. p. 1.) 
20* 
