20 
FRED. ELFVING. 
newly-discovered cell division in the Pollen-bodies, and on 
the other in studying the relations of the nuclei in the 
Pollen-tube. 
The reason why the fact of these Pollen-bodies having 
several cells has been overlooked by investigators, is pro- 
bably altogether owing to the want of a suitable method 
of investigation. For if the phenomena which take 
place show' themselves with surprising clearness in some 
plants, even without using particular reagents, yet, in 
general, little can be gained by the examination of fresh 
material ; and the reagents formerly used by botanists 
rendered little or no assistance. 
Osmic acid, wdiicli has lately come into use, proved to be 
an invaluable aid in these investigations. This acid has 
been used by Strasburger with great success in his investi- 
gations concerning the Division and Fertilisation of Cells. 
After I had tried several other means for clarifying my 
specimens I used the osmic acid alone, and that only in a 
solution one per cent, strong. It is always of great advan- 
tage to add some kind of colouring material to the specimens 
preserved in osmic acid ; sometimes it is quite indispensable 
to do so. A solution of carmine, to w'hich a little glycerine 
was added, usefully served as such. By these means pre- 
parations can be obtained after a space of twenty-four hours 
w'hich, in the way of clearness, leave nothing to be wished 
for. It is very useful to break up the Pollen-bodies, if they 
are large and richly filled with granular or oily contents, 
immediately after the osmic acid has been added ; this can 
be done by pressing on the glass cover ; for if left w'hole they 
may colour slowly or not at all. This is especially useful 
w'hen it is desired to see everything quickly. The nuclei 
are in this way pressed out and immediately fixed, together 
with the rest of the contents of the cell. It is often even 
possible to get in this manner a view of nuclei in the act of 
dividing ; colouring with carmine is naturally also here of 
great use. Plants with many-flow'ered inflorescences are 
especially suited for these investigations. If the first 
blossoms of such a plant have opened, it is easy to find all 
tlie younger stages of development in the buds above one 
another. The vegetative cell is, however, always (the case of 
the Cyperaceae alone excepted) formed in those Pollen-bodies, 
which are separated from one another; that is to say, if they 
ever do separate. 
In order to study the relations of the nuclei in the Pollen- 
bodies, I cultivated these in many and different solutions. 
This I did in the usual way — viz. in suspended drops in a 
