CHANGES IN CELL-ORGANS OF DROSERA ROTUNDIFOLIA. 395 
of the later stages of stimulation were specially well fixed, and 
they stained with great precision. 
Manu’s watery picro-corrosive fluid is in every way satisfac- 
tory, especially in its action upon control leaves. It both keeps 
the leaves expanded and preserves the dark colour of the glands. 
Though it causes some shrinkage of the protoplasmic body 
from the cell wall, it does not destroy any of its characters, 
and the points of attachment that remain in spite of the 
shrinkage serve to bring into evidence the fact that the proto- 
plasmic bodies of neighbouring cells are intimately connected 
with the cell wall at corresponding places, and so are probably 
in connection with each other. Further, material fixed in 
the watery fluid takes the stains with most satisfactory 
precision. 
The formula for this fixing fluid is as follows :—Saturated 
HgCl, in 3 per cent. NaCl, 1 part. Saturated solution of 
picric acid in Aq. Dest., 3 parts. This fluid has a specific 
gravity of 1020. 
The material was left in this for twelve hours, then trans- 
ferred for twelve hours to a saturated solution of corrosive 
sublimate in normal saline, and afterwards dehydrated in 
alcohol of gradually increasing strength, being placed in 50 
per cent. alcohol for four hours; 60 per cent., four hours; 70 
per cent., about ten hours (i.e. all night) ; 80 per cent., five 
hours; 90 per cent., five hours ; absolute alcohol, ten hours ; 
then next day into two further changes of absolute alcohol. 
Chloroform was next introduced into the bottom of the vessel 
with a pipette. An hour was allowed to elapse after the tissue 
had sunk in the chloroform ; the fluid was then all poured off, 
and fresh chloroform substituted, and this was changed once 
more after six hours. Paraffin of 52° melting-point was next 
added in small pieces, until saturation at a temperature of 
30° C. was reached. The tissue was then placed in a warm 
chamber heated to the melting-point of the paraffin, a little 
more melted paraffin added, and then the chloroform was 
allowed to evaporate slowly. Sections were cut 5:08 yu thick 
by a Cambridge rocking microtome, fixed on glass slips in 
