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Some Methods for the Study of Plastids in 

 Higher Plants. 



D. M. MOTTIER. 



The following methods have been found to be satisfactory in the studj* of 

 the primordia of ehloroplasts, leiicoplasts, and other apparently similar 

 bodies in cells of liverworts and higher plants that are known under the 

 name of chondriosmes. 



Fixing. 



Chrom-osmic acid is the fixing agent chiefly used, and in the following 

 proportions : 



Chromic acid, 1 % 17 cc. 



Osmic acid, 2 % 3 cc. 



Glacial acetic acid 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-kaernatoxylin stain. As a counter stain orange 

 G dissolved in clove oil is sometimes very desirable. 



Procedure with the Iron-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 (NH 4 )2 Fe2(S0 4 ) 4 ' 24 H 2 0. The preparations 

 are now poured off with water and stained over night in a 5 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 



