8 MICRO-ORGANISMS AND DISEASE. [CH. r. 



out properly, small bits about a half to one cubic inch of 

 tissue being placed in alcohol, or better in Miiller's fluid, and 

 kept there ; in the first instance, for two to five days ; in the 

 second, for from one to three weeks or more. Then small 

 bits are cut out, of which it is desired to make sections. 

 "Those hardened in spirit must be soaked well in water to en- 

 able the material to freeze, then superficially dried with 

 blotting-paper, and then used for cutting sections with Roy's 

 microtome. Those hardened in Miiller's fluid are at once 

 superficially dried with blotting-paper and cut. When 

 making sections with Williams's freezing microtome it is 

 necessary to soak the material first in gum mucilage and then 

 to freeze and to cut. Fresh tissues are at once cut with the 

 freezing microtome, the sections placed in 0'6 per cent, of 

 saline solution, floated out and well spread out, and then 

 stained by transferring them in this condition, i.e. well spread 

 out, into a w r atch-glass containing the dye. The sections of 

 hardened tissues are floated out in water, well spread out, 

 and then transferred to the dye or dyes as the case may be. 



It is necessary to prevent too much shrinking of the 

 sections, especially those of fresh tissues ; for this reason it is 

 advisable to float the sections in the saline solution or water, 

 as the case may be, on a broad lifter or spatula, to spread 

 them well out upon it, and to transfer them carefully into 

 the dye, then into the dish with water used for washing off 

 the excess of the dye, to transfer them, well spread out on the 

 lifter, to alcohol, then after several minutes to oil of cloves, 

 and finally on to a glass slide, on which they are mounted in 

 the usual manner with Canada-balsam solution, the excess of 

 clove-oil being previously drained off, 



It is advisable, although not absolutely essential, to keep the 

 sections in a well spread-out condition for a few seconds in 

 alcohol before placing them into the dye. 



