45 



and trouble necessary to prepare tissues in this 

 way. It may, be pointed out : — 



1. That the times usually given for immersion 

 in paraffin and other reagents are unnecessarily 

 long. 



2. That the use of two paraffins for 

 embedding, a soft and a hard, is an unnecessary 

 and even harmful procedure. 



3. That an elaborate apparatus for the 

 paraffin bath is unnecessary {vide later). 



4. B}' using fiat and very thin pieces of 

 material, sections of considerable area may be 

 obtained in a minimum of time. It is necessary 

 to cut thin slices of the raw material (i mm. or 

 less in thickness), and place these upon a small 

 piece of paper or coverglass before placing in the 

 alcohol to harden. The paper keeps the slab from 

 becoming distorted, and enables one to cut sections 

 of the full area of the slab, say two-fifths inch 

 square. 



5. By placing minute pieces of tissue (in 

 slabs on paper, if a section of some size is needed) 

 directly into absolute alcohol, fixing, hardening,and 

 dehydration can be accomplished within an hour. 



Necessary Apparatus for Paraffin Sections 



1. Cambridge Rocking Microtome. — The or- 

 dinary form is all that is necessary, costing about 

 five pounds. It is convenient to have a ball and 

 socket adjustable holder, which enables one to 

 change the angle of the block without remelting 

 the paraffin. 



2. I^a^ors.— These may be hollow-ground 

 on one side, or on both, to a varying depth. For 



