ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 163 



•with a glass cemented with balsam ; but considerable practice is 

 required in this part of the work, as the preparation being very thin, 

 is liable to be broken into pieces by very slight overheating. The 

 superfluous Canada balsam around the slice should be first carefully 

 scraped off with a sharp-pointed knife, and the slide well washed in 

 spirit of turpentine, using a camel-hair brush to clean the section 

 thoroughly. A little Canada balsam should then be dropped upon 

 the centre of the section, and a clean cover-glass, heated a little, should 

 be laid upon it while yet warm, and pressed down upon it, so as to 

 force out the air-bubbles if any remain. 



The slide on which the section still remains should not be too 

 hot, otherwise the gum will become soft and the preparation spoiled. 

 Several preparations may be quite easily made from one moulding, 

 and when mounted, labelled and laid aside for future examination. 



Mineral particles, no matter how small, can be cut into sections 

 in the manner described. 



Cedar-wood Oil for Paraffin Imbedding.* — Mr. A. B. Lee ad- 

 vocates the use of cedar-wood oil for clarifying tissues previously to 

 imbedding them in paraifin. 



The object is steeped in the oil, and then transferred to a bath 

 of pure paraffin, or, if it be a delicate structure, first of all to a 

 mixture of oil and paraffin. The cedar-wood oil clarifies very rapidly, 

 and the object absorbs the paraffin quickly and thoroughly, so that 

 it is only necessary to leave it for a very short time in the paraffin. 

 The length of time that the object is left in the oil is of no moment, 

 as it does not become brittle or over-hardened ; treatment with this 

 oil renders section-cutting very easy, and the method of procedure is 

 exceedingly simple. 



Apparatus for Imbedding^ Preparations specially adapted for 

 the Nervous System. f — Instead of the ordinary clamp arrangement, 

 Dr. S. V. Stein recommends a small metal case, open above, and to the 

 bottom of which a clasp, with or without a slot, is fitted. The walls 

 are formed by two rings. The upper ring, 30 mm. high, is pushed 

 over the lower one, 10 mm. high. To make the imbedding mass adhere 

 firmly, the floor of the box is fitted with three screws which project 

 into the cavity for a distance of 4 mm. 



When used, the upper ring is oiled and adjusted. The imbedding 

 mass (one part oil and two parts wax) is then poured into the case 

 until the screws are covered. After this has cooled down a little, the 

 object is placed thereon, and the rest of the space filled up. The mass 

 sets in a short time. The upper ring is then withdrawn, and there 

 remains a wax column in which the object is firmly fixed. The 

 sections are cut under water. This procedure is easily effected by 

 the Leiser or Schanze microtome. The size and shape of the case 

 Ground or oval) depends on the form of the part of the nervous system 

 (a hemisphere, &c.). 



This method has the advantages — (1) that the specimen is not 



* Zool. Anzeig., viii. (1S85) pp. 563-4. 



t Centralbl. f. d. Med. Wiss., 1884, pp. 120-6. Of. Virchow and Hirsch's 

 Jahresbericht (for 1884) 1885, p. 41. 



M 2 



