1894.] Microscopy. 721 
2. The object is placed in toluol containing some paraffine in solu- 
tion. The alcohol diffuses in the excess of toluol, and the celloidin 
solidifies. Imbed as before. 
In both cases care must be takef to avoid shrinkage, which occurs 
if the eelloidin is solidified in pure paraffine. 
The object thus imbedded in paraffine is sectioned in the usual way. 
The ribbons of sections are fixed to the slide by means of the ordinary 
albumen fixative, or by the aid of pure water. In the latter case, the 
strips cut to the length desired are placed on a clean slide slightly wet 
with water. Then a little water is added by means of a brush, just 
enough to barely float the sections‘ The slide is then heated so as to 
soften the paraffine without melting it. The sections expand readily. 
It remains only to drain off the water and let the slide dry completely. 
If desired the celloidin may be removed by the mixture of alcohol 
and toluol which dissolves at once both the paraffine and celloidin. 
Then, after washing with toluol, the sections may be mounted in bal- 
sam in the usual way. If they are to be colored on the slide, they 
should be washed with alcohol and water. 
On the Fixing of Paraffine Sections to the Slide.—A com- 
bination of the water method of Suchannek and Heidenhain with the 
albumen method of Mayer has been found very useful as it does away 
with the slow-drying of the former method and still permits the ready 
arrangement of the sections and their expansion and flattening. 
A slide, cleaned with only ordinary care, is covered by means of the 
finger with the least possible amount of Mayer’s Albumen. By means 
of a small brush the upper surface of the slide is then flooded with 
water and the brush, still slightly wet, is used for picking up and ar- 
ranging the sections or ribbons. The brush may then be used for re- 
moving the excess of water, and the slide slightly warmed fora few 
moments on a water-bottle, care being taken that the sections do not 
melt. The sections soon expand and float upon the water which 
should be drained away and slide placed a second time upon the 
water-bath. After remaining about fifteen minutes the paraffine may 
be melted and the slide plunged into turpentine or some other solvent 
of paraffine.—H. C. Bumpus, Marine Biological Laboratory, Woods 
Holl, Mass. 
*The following note by Dr. Bumpus suggests an improvement. 
