ON WANDERING CELLS IN ECHINODERMS. 117 
be easily replaced by means of a mounted needle. If too little 
alcohol has been used they wil! not have been enabled to 
extend and become flat, and they will be wrinkled more or 
less, according to their previous condition. 
When all the alcohol has evaporated, the paraffin may be 
just melted and then dissolved with benzol or xylol, or seven or 
eight parts of benzol to one part of turpentine, the latter pre- 
venting absolute drying should the benzol evaporate. Canada 
balsam may then be dropped on and the cover-glass applied, 
or the slide may be put through absolute alcohol and stained 
and mounted in any desired manner. 
Care should be taken that the warm plate is not too hot. 
If it is, the paraffin melts completely, the sections are unsup- 
ported, and are liable to be torn by the connection currents of 
the heated alcohol. Care should also be taken that all the 
alcohol is evaporated before steps are taken to mount in 
balsam, or a cloudy result will ensue. 
By this method sections can be mounted quite flat without | 
any wrinkles; indeed, apparently hopelessly crumpled sections 
can be mounted with success. It is much less trouble than 
Gaskell’s warm water method, and is as satisfactory. 
If staining on the slide is intended, I recommend the use of 
alcohol as fixative rather than egg-albumen-glycerin, or clove- 
oil collodion, because no stained material (albumen or collodion) 
results, as sometimes occurs in those methods. As regards its 
fixing power, I may mention that I have put slides straight 
from absolute alcohol to a watery stain without displacement— 
the use of intermediate grades of alcohol is recommended ; 
and also have stained, restained, and remounted a slide three 
times successfully. I have used the method for nearly two 
years. 
