DEC 11 1901 
pe 
Ae pS 
REW YORK 
BOTANICAL 
AND 
NORTHERN MICROSCOPIST. 
JANUARY. 1884. 
No. 37. 
PRACTICAL: PROCESSES IN VEGETABEE 
HISTOLOGY: 
By L. OLIver, in Rev. Sci. Nat., 1882. 
Taken from the Journal of the Royal Microscopical Society. 
(Continued from page 322, Vol. IIL.) 
II. FIXATION OF FORMS. 
ae ternary parts of the plants being generally tolerably rigid, it 
is only necessary to fix the proteid matter (protoplasm, nuclei, 
vibratile, cilia, &c.). The following agents are employed for this 
purpose. 
Absolute alcohol. When absolute, alcohol fixes the protoplasm 
without contracting it. It can be made to act directly on the pre- 
paration to be examined, or upon the organs before making sections. 
Strasburger has studied in the latter mode the formation of the cells 
in Iris pumila. By immersing Sfirogyra orthospira in absolute 
alcohol at different hours of the night he succeeded in fixing the 
different phases of the division of the nucleus in this alga, which it 
then became very easy to study by daylight (without its changing) 
the day after and the following days. The same observer succeeded 
in retarding division until the morning by placing the Spzvogyra 
in a room without heat in November. He was thus able to follow 
under the Microscope all the phenomena of the division, and to fix 
them at the most suitable moment by immersing the plant in abso- 
‘lute alcohol. 
Chromic acid.—\ Guignard has successfully employed chromic 
acid to fix the nuclei in the embryo-sac in the Mimose.* The 
good results he obtained with it mark this reagent as one of the 
most valuable in vegetable microchemistry. 
Osmic acid.—Osmic acid, whilst fixing the form, has the advant- 
* Bull. Soc. Bot., 25th June, 1880. 
VOL. IV. 
