NUCLEAR DIVISION. 7 
the development of the karyokinetic spindle in both vegetative and 
reproductive cells agrees essentially with that described for Dictyota, 
In the diatoms the development of the spindle as described by 
Lauterborn (’96) is singular and without parallel in the plant king- 
dom. According to this author, the spindle develops directly from 
the centrosome by a division of the same or by budding. We shall 
refer to this phenomenon beyond in the section dealing especially with 
the centrosome. In the red alge the development of the karyokinetic 
figure is known somewhat in detail only in Coral/ina offictnalis. In 
this plant, Davis (’98) finds that the spindle arises through the agency 
Fic. 3.—Second mitosis in tetraspore mother-cell of Dictyota. 
H-K, prophase, showing origin of spindle. L, a nearly mature spindle. 
of centrospheres which undergo a great change in size during mitosis. 
The persistence of these bodies was not followed from one cell genera- 
tion to the next. The paucity of our knowledge of nuclear division 
in the red alge precludes any further mention of the subject in this 
group of plants. So far as is known to the author, no centrospheres 
or centrosomes have been authentically observed in the green algz. 
ERYSIPHE COMMUNIS. 
For the fungi, the most accurate and complete account of karyoki- 
nesis is to be found in the classical work of Harper (’97) on certain 
Ascomycetes. Asan illustration of the process in this group of fungi, 
which is probably best known cytologically, a brief account of mitosis 
will be given as described by Harper in the ascus of Zryscphe 
communis. 
