AMYLASE IN THE LIVING CELL 119 



A few watch glasses ; 



Absolute alcohol ; 



Clove oil ; 



Alcoholic iodine solution ; 



Microscope sUdes and cover glasses ; 



Xylol ; 



Canada balsam ; and 



Shellac varnish. 

 In order to make a section laterally through the embryo, 

 a softened barley grain should be embedded laterally into a 

 block of paraffin, say one inch cube, if the razor and not the 

 microtome is to be used. The grain is easily embedded by 

 melting a little of the paraffin in the middle of one of the sides 

 of the block with a hot glass rod, carefully placing the grain 

 in the little melted pool of paraffin and allowing it to set 

 thoroughly hard. With a httle practice it is possible with a 

 sharp razor to cut very fairly accurate thin lateral sections of 

 the grain ; a number of these can be cut until the embryo 

 is fully exposed, when the section of the grain will have the 

 appearance roughly as shown in Plate II (ii). A number of 

 these sections should be cut and immersed in a little absolute 

 alcohol, contained in one of the watch glasses, in order to harden. 

 As the moisture in the section is reduced by alcohol the section 

 becomes hard. It is next transferred to a watch glass containing 

 clove oil, in order to clear it and render it transparent ; it is 

 then irmnersed in xylol to remove the excess of clove oil, placed 

 on a microscope slide, covered by a cover slip and examined. 

 If a permanent preparation is required it may be dipped 

 into an alcoholic solution of iodine and then into picric 

 blue, and the excess of iodine and of colour washed out 

 with alcohol. The iodine stains the starch granules purplish 

 blue, and the aleurone (or albuminoid) layer yellow. The 

 remaining tissues are coloured blue by picric blue. 

 I The section is now ready for mounting ; it is placed in the 

 centre of a microscope sUde, covered with a drop of Canada 



