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SomE METHODS FOR THE STuDY OF PLASTIDS IN 
HIGHER PLANTS. 
D. M. Mortier. 
The following methods have been found to be satisfactory in the study of 
the primordia of chloroplasts, leucoplasts, and other apparently similar 
bodies in cells of liverworts and higher plants that are known under the 
name of chondriosmes. 
FIXING. 
Chrom-osmie acid is the fixing agent chiefly used, and in the following 
proportions: 
hiro mlera cid slo re a ee ain areee Ue aR Mees Ot Laer 17 ce. 
COPEITDNIE I VEL bP 9 i ts Sas Oe Ae dO NE Me SRS 3 ce. 
RerleLGt a CC MLC AGI y 15, s wht ethane lve) amcor nage Bie 3 drops 
The specimens remain in this fluid from 36 to 48 hours, after which they 
are washed 12 to 24 hours in flowing water, or in several changes of water if 
flowing water is not available. 
After careful dehydration the specimens are brought into paraffin, using 
chloroform as the solvent. Sections from 3 to 5 microns in thickness are 
cut, depending upon the nature of the tissue under consideration, and stained 
in the well-known iron-alum-haematoxylin stain. As a counter stain orange 
G dissolved in clove oil is sometimes very desirable. 
PROCEDURE WITH THE [RON-HAEMATOXYLIN. 
After the preparations have been freed from paraffin and from the solvent 
used in removing the paraffin (turpentine or xylol) by means of absolute al- 
cohol, they are allowed to stand in the mordant from two hours to over night. 
As a mordant a 3 per cent. aqueous solution of the double iron salt is used 
(ferric ammonium sulphate (NH4,). Fe.(SO,), 24 H.O. The preparations 
are now poured off with water and stained over night in a 2 per cent. aqueous 
solution of haematoxylin. From the stain they are again poured off with 
water and destained with the above iron salt. The destaining is watched 
under the microscope. After the desired stain has been reached, and this 
