1918] BUCHHOLZ—PINUS 193 
Mountinc.—After the last washing 10 per cent glycerine is 
added and the material set aside to evaporate in a place protected 
from dust. When the concentrated glycerine is washed out with 
95 per cent alcohol, great care must be exercised to prevent injury 
to the preparation. Several changes of alcohol will be necessary 
to remove all the glycerine, and after washing twice in absolute 
alcohol the 1o per cent Venetian turpentine is added and the 
watchglass placed in a desiccator. It is not desirable to allow the 
Venetian turpentine to get too stiff, as the specimens will be broken 
in mounting. If more of the ro per cent Venetian turpentine is 
added to thin it down, as is frequently done, it causes the cells to 
swell, the cell walls separating from the protoplasts, leaving a 
permanent clear space between. If the Venetian turpentine must 
be thinned down, it should be done by adding about 85 per cent 
Venetian turpentine. The preparations may be picked up for 
mounting by means of a needle with a curved point, or a spear 
point. In handling them they should be picked up in a drop of 
Venetian turpentine and not by attempting to pull them out. 
Preparations were also made by changing the embryos from 
concentrated glycerine into glycerine jelly. These mounts were 
not very satisfactory and compare very unfavorably with those 
prepared in Venetian turpentine. 
METHODS FOR SERIAL SECTIONS.—The ovules were prepared for 
the fixing agent by removing the testa completely from the game- 
tophytes. This can be done without crushing the latter by slicing 
away one side of the ovule down to the gametophyte with a sharp 
scalpel, then slicing away the edge, whereupon the gametophyte 
may be pried out without injury by inserting the point of the 
scalpel under it. For the early proembryo stages it is not neces- 
sary to remove the gametophytes from the testa, but a slice should 
be cut from one side, or better from opposite sides, to permit 
good fixation. The older testa cuts with difficulty, and it was not 
possible to get good sections of P. Banksiana when the coat had 
been left on in stages after the early elongating suspensor. 
The naked gametophytes were removed and placed for 20-30 
hours in the killing fluid, consisting of a chromic-acetic mixture ' 
(3 per cent chromic, 1 per cent acetic). After washing overnight 
