AND HOW TO USE IT. 



246 



has accumulated on the iron, it must be floated off into a saucer 

 of water, which may be cold or warm. From the bowl of water 

 into which they are put first, they are transferred to a conical glass 

 filled with water, in which they gradually subside. All the gum 

 must be got rid of, which is accomplished by changing the water 

 several times. When all the gum is dissolved, transfer the sections 

 to one or other of the following fluids till they are required. The 

 sections, when cut, should be kept in a glass-stoppered bottle. 



Preservative Fluids:— (i) Ordinary methylated spirit. (2) 

 Glycerine, i ounce; water, t ounce; carbolic acid, 4 minims. (3) Dr. 

 David J. Hamilton, of Edinburgh University, recommends glyce- 

 rine and distilled water, of each 4 ounces ; carbolic acid, 3 drops. 

 Boil and filter. The addition of 2 ounces of alcohol is advisable. 



Gum and Syrup Preserving Fluid (Cole). — Specimens may 

 be kept the year round in gum and syrup, having a little carbolic 

 acid in it ; if the operator chooses, he can then freeze and cut the 

 tissue so placed at any moment he likes. 



To make the Gum and Syrup. — ^Take of gum mucilage (B.P.) 

 5 parts. This is made by placing 4 ounces of picked gum acacia 

 in 6 ounces of distilled water, and stirring occasionally until the gum 

 is dissolved. This is to be strained through muslin. Syrup, 3 

 parts, made by boiling i lb. of loaf sugar in i pint of distilled 

 water, and boiling ; add 5 grs. of carbolic acid to each ounce of the 

 above medium. Tissues may remain in this any length of time. 

 For brain, spinal cord, retina, and all tissues liable to come in 

 pieces, put 4 parts of syrup to 5 of gum. In cutting some 

 materials, such as retina, it is advisable to strain it en iiuissc before 

 freezing, otherwise the sections cannot be seen when placed in 

 water. The operator will do well to make the gum mucilage and 

 syrup separately, and keep them so till wanted. 



To cut Tissues soaked in Gum and Syrup Medium. — Take 

 a piece of tissue and press it gently between a soft cloth to 

 remove all the gum and syrup from the outside of the tissue. Set 

 the spray going, and paint on the freezing plate a little gum, then 

 put the tissue upon this and surround it with the mucilage, with a 

 camel's hair brush. In this way the tissue is saturated with gum 



