1885.] Microscopy. 215 
MICROSCOPY.! 
CALDWELL’S Automatic Microtome.2—This machine has been 
devised to save labor to the histologist by cutting a very great 
number of sections suitable for microscopic investigation in a 
very short time. The machine is worked by hand and may easily 
be made to deliver in one continuous band, accurately cut sec- 
tions at the rate of 100 per minute. To use it, however, to the 
best advantage, it is well to drive it by means of some motor, the 
fly-wheel being already provided with a groove for thé reception 
of the cord coming from the motor. Where there is sufficient 
pressure and supply of water, a simple form of water motor seems 
the most appropriate and least expensive. 
Method of using the Microtome—Place one of the cylindrical 
vessels supplied with the machine upon a piece of paper on a 
glass plate, and pour into it sufficient melted paraffine to fill it. 
As this cools the paraffine will contract, and will leave a hole, 
which must be filled up with more melted paraffine. 
Melt a small quantity, say an ounce, of imbedding material in 
some suitable vessel; a small copper pan or a porcelain crucible 
answers very well, if care is taken not to allow it to become hot- 
ter than is sufficient to thoroughly melt it. Take a piece of glass 
and smear it with a very small quantity of glycerine, to prevent 
the imbedding material from sticking to it. Then pour the melted 
material on the glass in small quantities at a time, so as to get a 
layer nearly a quarter of an inch thick. This when cut up into 
Suitable pieces with a knife does very well for imbedding small 
objects. If larger objects are required, it is well to have two 
pieces of brass of the form shewn in Fig. 5, which, when placed 
together, will form a cavity half an inch in depth and of any de- 
sired length up to an inch or more; this cavity may be filled with 
the melted material in the manner already described, and the 
object to be cut must then be placed in position while the mate- 
rial is fluid. Zz is well to cool the material as rapidly as possible 
by placing it in water as soon as it is sufficiently set. From the 
cake thus formed, or from the piece cast in the mold, cut the 
piece of the material containing the object, and with an old scal- 
pel, heated in a Bunsen flame, melt a small hole in the paraffine 
contained in the cylindrical vessel (Fig. 1 æ), and insert the piece 
of imbedding material containing the imbedded object; then with 
the heated scalpel melt a little of the paraffine round the base of 
the projecting piece, so as to give it firm support, and allow this 
to become thoroughly set. : 
Now remove the large brass plate from the top of the micro- 
tome (Fig. 1 4) and insert the vessel containing the imbedded 
object in the tube for its reception, having first oiled the tube 
1 Edited by Dr. C. O. WHITMAN, Mus. Comparative Zoology, Cambridge, Mass. 
? Quart. Jour. Micr. Sc, XXIV, Oct., 1884, p. 648. 
