SPERMATOPHYTES—ANGIOSPERMS 
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of B, or even 1 c.c. of B. If the regular formula is used, we should 
let it act for an hour, and then replace it by A, without any osmic 
acid. The osmic acid undoubtedly accelerates the killing of the 
protoplasm. This is seen more readily in animals. If Cycloys be 
brought into 30 c.c. of the solution A, the animals will swim for awhile; 
if 5 or 6 drops of 1 per cent osmic acid be added to the solution, the 
animals cease their movements almost instantly. Doubtless the 
osmic acid has the same effect upon plant protoplasm. Where 
fixing is slow, very few mitotic figures are found with the chromo¬ 
somes midway between the equator and the poles. The addition of 
10 drops of 1 per cent osmic acid to 50 c.c. of the solution just men¬ 
tioned will secure as large a proportion of anaphases as solutions 
which are stronger in osmic acid, and there is no disagreeable 
blackening. 
Farmer and Shove, in studying these mitoses and also vegeta¬ 
tive mitoses in Tradescantia , secured better results with a mixture 
of 2 parts of absolute alcohol and 1 part glacial acetic acid. They 
allowed the fixing agent to act 15 to 20 minutes, then washed in 
absolute alcohol, and imbedded by the usual methods. This propor¬ 
tion of acetic acid seems entirely too large for any accurate work 
with chromatin, and we doubt whether the structure of the cytoplasm 
is normal when so much acetic acid is used. 
The entire pollen mother-cell may be stained and mounted without 
sectioning. Two descriptions of technic appeared in 1912, one by 
Mann and the other by Pickett. Mann removes the pollen mother- 
cells before fixing and staining; Pickett fixes and stains the anther 
in toto and teases out the pollen mother-cells just before mounting. 
In Mann’s method, the anther is placed in a drop of water and 
the tip is cut off; a gentle tapping with a needle will then cause the 
pollen mother-cells to float out into the drop. Fix in Bouin’s fluid, 
4 to 8 hours, wash in 50 per cent alcohol until no color remains, and 
then stain in iron-haematoxylin. At this stage we should put the 
material into 10 per cent glycerin and follow the Venetian turpentine 
method. 
Pickett fixed entire anthers in chromo-acetic acid for 30 hours, 
washed in water for 24 hours, and then passed up to 80 per cent alco¬ 
hol. At this point, he stained in strong cochineal or Kleinenberg’s 
haematoxylin for 5 days, then completed the dehydration, cleared in 
cedar oil, teased out the mother-cells, and mounted in balsam. 
