720 The American Naturalist. [August, 
MICROSCOPY. 
New Method of Imbedding in a Mixture of Celloidin and 
Paraffine/—Messrs. Field and Martin recommend the following 
method as an improvement on those proposed a few years ago by 
Ryder and Kultschizky. The method permits of imbedding the ob- 
ject directly in a mixture of celloidin and paraffine. The mixture is 
prepared by using as a solvent, alcohol and toluol (toluéne) ; the lat- 
ter, taking the place of ether, makes it possible to dissolve paraffine in 
the celloidin solution. Proceed as follows: 
1. Make a mixture of absolute alcohol and toluol in equal parts. 
2. Soak some dry celloidin in toluol; after some hours, add a little of 
thealcohol-toluol? The celloidin swells up and dissolves. The solution. 
should have about the consistency of clove oil. 
3. Finally, add to this mixture some shavings of paraffine, obtained 
by scraping the surface of a block of this substance with ascalpel. In 
order to hasten the solution and increase the proportion. of paraffine 
the mixture may be heated a little. Above 20° to 23°, one runs the 
risk of precipitating the celloidin, which separates in a — 
granular mass. 
These mixtures prepared, the process of imbedding is executed in 
the following manner: The object, taken from absolute alcohol, is- 
placed in the alcohol-toluol. It is easily and quickly saturated, and 
is then placed directly in the imbedding mixture. The penetration is. 
more rapid than in the ordinary celloidin solution. As soon as satura- 
tion is complete, one may proceed to solidify the celloidin. This may 
be done in two ways: 
1. The object is transferred to a saturated solution of paraffine in 
chloroform, and when the solidification is complete (2-3ds.), the imbed- 
ding paraffine is carried out according to the well known method 
Bütschli. 
TEd. By Prof. C. O. Whitman, University of Chicago. 
*Bull Soc. Zool de France, XIX, p. 48, Mar. 18, 1894, and Zeitschr. f. wiss. 
Mikr., XI, 1, 1894 
*?The alcohol-toluol is added after the tuluol has been turned off. About 45cc 
is enough for 1 grm. of celloidin. This solution will dissolve about 4 grm. of 
paraffine (melting at 56?) at ordinary room temperature. 
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