for Microscojjical Examination. 263 



it will float off ; or it may be displaced from the blade with a camel's- 

 hair brush. In removing thus, great care is necessary, otherwise 

 the section will be lacerated. As regards wetting the blades, the 

 same precaution obtains here as in the method described in Sec- 

 tion II. 



(B.) Finer sections can always be made when the tissue is firmly 

 supported. For this purpose embedding is necessary. Various 

 mixtures have been proposed by different authorities, of which the 

 following is at best an incomplete list : — 



Strieker * employs equal parts of white wax and olive oil. Drs. 

 Urban Pritchard and Ferrier f recommend a mixture composed of 

 solid paraffin, five parts ; spermaceti, two parts ; lard, one part. 

 His X covers the object in pure paraffin, and a mixture of white wax 

 and cocoa-butter is used by Mr. Moseley. § 



Of the above mixtures, perhaps the best and cheapest is the wax 

 and oil mass. In its preparation the finest white wax and purest 

 olive oil must be used ; the proportion of wax to oil will greatly 

 depend upon the firmness of the tissue to be embedded. The 

 greater the density, the larger will be the amount of wax required, 

 and vice versa ; but the mass generally used is made as follows : — 

 Equal parts of the ingredients are placed in a porcelain dish and 

 heated till all the wax has melted, being continually stirred with a 

 glass rod, that the mixture may be well incorporated ; the mass is 

 now ready for use. If the material from which sections are to be 

 made has been hardened in aqueous solutions, it must be removed 

 and steeped in ordinary methylated or absolute alcohol, so that the 

 water may be replaced by spirit; this will occupy a longer or 

 shorter time, according to the strength of the alcohol and size of 

 the tissue. When perfectly saturated with spirit, an oblong piece 

 is to be removed from it with a scalpel. A paper box must now be 

 made according to the size of the piece, and about half as long 

 again, the breadth and depth being in proportion ; say, for example, 

 the piece to be embedded is 1 in. long, and J in. in breadth and 

 depth. We must take a piece of stiff, well-glazed paper, 1\ in. 

 long and \\ in. broad, which is to be folded on itself for about \ in. 

 on both sides in the long diameter, then the ends for a similar 

 distance, so that it now appears to be only \ in. broad and \\ in. 

 long. Now unfold the sides to half the distance, so that four walls 

 are formed ; the triangular pieces projecting from the corners are 

 to be folded on the ends, so that they overlap each other, and, kept 

 in position with a little gum or a pin, our box is now complete. 



* Strieker, in Introduction of ' Manual of Human and Comparative Histology,' 

 translated for New Sydenham Society, by H. Power, M.B., &c. 



t Pritchard and Kutherford, p. 16, No. 45, ' Quarterly Journal of Microscopical 

 Science,' and p. ,382, No. 48, ibid. 



\ Frey, loc. '-it. 



§ Moseley, p. 337, No. 10, ' Quarterly Journal of Microscopical Science.' 



