1885, ] Microscopy. 1247 
which can be rolled in like the finger of a glove by the action of 
a retractor muscle. The eversion is effected by forcing blood 
from the body-cavity into the lumen of the tentacle. If, when 
the tentacle is fully extended, a thread be quickly tied around its 
base so as to prevent the escape of the blood, the infolding pro- 
cess cannot take place, and the hardening fluid may then be safely 
applied. Flemming recommends treatment with bichromate of 
potassium (4 p. c.) This method enables one to obtain sections 
of the eye in the extended condition of the tentacle. 
IMBEDDING IN PARAFFINE.— Clarifying media—Cedar-wood oil 
is recommended by Lee’ as a clarifying medium on various 
grounds, the more important of which are the following: 
I. It clarifies as rapidly as clove oil. 
2. It does not render the object brittle or excessively hard. 
3. It is a much better solvent of paraffine than clove oil; and 
hence only a short paraffine bath is required. 
4. The penetration of the paraffine is not only more rapid, but 
also more thorough. 
Holl? recommends toluol, which he finds can be used to greater 
advantage than chloroform, especially with large objects. The 
largest objects should be left one day in toluol, and one day in 
the paraffine bath ; small objects require correspondingly shorter 
times. 
Imbedding Box.—A convenient box, introduced by Dimmock, 
may be made of two pieces of type metal (or better of brass). 
As will be seen from the accompanying diagram, each piece of 
casi ee 
— 
metal has the form of a carpenter’s square. A convenient size 
will be found in pieces measuring 5™ (long arm) by 3 (short 
arm) and 7™ high. With such pieces a box may be constructed 
at any moment by simply placing them together on a plate of 
glass which has previously been wet with glycerine, and gently 
warmed. The area of the box will evidently vary according to 
the position given to the pieces, but the height can be varied 
only by using different sets of pieces. 
It is well to imbed in a thin layer of paraffine, so that the 
object, after cooling, may be cut out in small cubical or pyramidal 
1 Zool. Anz., No. 205, p. 563, Oct., 1885. 
2Zool. Anz., No. 192, p. 223, April, 1885. 
