164 Mottier.—Nuclear and Cell Division 
Deutschen Botanischen Gesellschaft. Since that time I have 
been able to make a somewhat exhaustive study of the 
entire process of nuclear and cell-division in both vegetative 
cells and tetraspore mother-cells, and the results of this study 
are set forth in the following pages. 
Method. 
To the cytologist the method by which results are obtained 
is always of prime importance, since the improvement of 
older methods or the discovery of new ones is one of the 
principal channels through which progress in cytology is 
possible; and as certain features in the method used proved 
somewhat surprising, a brief statement of the same may be 
useful to others pursuing similar lines of investigation. 
In the beginning of my study the same combination of 
chromic-osmic-acetic acid, which gave such remarkably good 
results for the pollen mother-cells in Lilium and other 
higher plants, was used, except that the solution of chromic 
acid was made from sea water, namely: Solution A, 
1 or J°/ o chromic acid (in sea water) 16 cc. 
2 °/ o osmic acid . . . 3 cc. 
Glacial acetic acid . . . 1 cc. 
If the objects were left in the fluid for a longer time, 
one-half per cent, chromic acid was used instead of one 
per cent. 
Material fixed in this fluid, when worked up immediately, 
proved to be so blackened, that preparations, even of very thin 
sections, were unsatisfactory and generally worthless. Much 
time and patience were required to determine the amount 
of osmic acid necessary to fix cytoplasmic structures well, 
with as little blackening as possible. At first the above 
solution A was diluted with an equal volume of sea water, 
which I shall designate solution B. When the solution was 
diluted one-half, one per cent, chromic acid was always used 
in the original. This also proved to blacken too much. 
Several solutions were then tried, in which one to four drops 
