184 W. WALDEYER. 
work of Schewiakoff (178) he suggests the possibility that in 
Protozoa the spindle figure arises from the nuclear substance; 
he connects this with the permanent demarcation of the nucleus 
from the cytoplasm. 
In Spirogyra those spindle-threads which have united with 
one another at the equatorial plane, remain for some time as 
“connecting threads ” during the separation of the daughter. 
nuclei (Strasburger makes no mention of van Beneden’s 
“filaments réunissants,” which must be distinguished from 
the spindle-threads). Finally, Strasburger believes that all the 
spindle-threads are converted into cell-protoplasm, but that this 
part of the protoplasm will immediately be used up again for 
the nourishment, as well as for the completion of the daughter- 
nuclei. 
Flemming (63) looks on a large part of what becomes the 
protoplasm of the daughter-cells as referable to the remains 
of the threads; but it does not necessarily follow that these 
threads also had their origin from the protoplasm. On the 
contrary, if the threads arise from the mother nucleus, and are 
converted into cell-substance, it is to be regarded as an im- 
portant factor in the process of hereditary trans- 
mission. “ It is possible to assign a certain predisposition to 
the cell-body.” Flemming, however, especially points out that 
he has always regarded the chromatic alone as the essential 
nuclear substance. The relation, too, of the spindle figure to the 
formation of the cell-membrane is important. In plant-cells it 
consists essentially in the formation of small knob-like thick- 
enings of the spindle-threads at the commencement of cell- 
division. The group of knobs (“dermatosomes ” of Weisner 
(207, in another sense) and of Strasburger) forms Strasburger’s 
“cell-plate.’ They indicate the plane of division of the 
nucleus and cell, and later on are in plant-cells converted into 
the cell wall, which consists essentially of a fusion of gradually 
increasing dermatosomes. 
While the membrane is developing, numerous other thread 
unions arise, as Strasburger has shown very decisively in his 
latest contribution (191). Partition walls are not present in 
