SECTION CUTTING. 123 
illuminated. ‘There are two ways of accomplishing this: by 
teasing and by cutting sections. 
The easier method is by teasing. ‘To do this a portion of 
the object is placed ona slide with the addition of a few 
drops of water, alcohol, glycerine or neutral salt solution ac- 
cording to the nature of the specimens and the objects or 
portions which it is desired to see. ‘Then with two dissecting 
needles the tissue is teased or pulled into shreds, and then 
examined under the microscope, or mounted permanently 
after any desired method. 
Teasing produces good results in fibrous tissue where it is 
desired to isolate the fibres, as in nerves, muscles, connective 
tissue, etc. At other times it does not work so well. 
Section cutting is, however, the most universal and in the 
majority of cases the best method of preparing substances for 
examination, but at the same time it requires more time to 
accomplish. ‘The various processes can conveniently be taken 
up in the following order: hardening and decalcifying, em- 
bedding, cutting and freeing from the embedding material. 
Fresh tissues are generally either too soft, or in the case of 
bones, teeth, scales, and shell too hard to admit of being read- 
ily cut and hence certain steps must be taken to prepare them 
for the razor. 
Suppose we have an object, an embryo tadpole for instance, 
of which we desire to obtain sections. ‘This in its natural con- 
dition would be far too soft and must be hardened. This 
hardening may be accomplished in various ways. The most 
common method is first to place it for a few hours in weak 
alcohol (about 40 percent.) ; it is then transferred to stronger 
