APPENDIX 313 



V. TRANSFERRING SECTIONS. FIXATIVES. FLUIDS 

 FOR MOUNTING. 



A. Transferring a number of sections from one fluid 

 to another. In preparing a number of sections for class work, 

 it is convenient to transfer them from fluid to fluid by means of 

 a horse-hair filter. A piece of horse-hair tissue, such as is used 

 by wig- makers, is sewn over a ring, provided with a handle. The 

 fluid with the sections is poured on this ; the sections remain, 

 and float off" readily when the filter is placed in fluid, with the 

 surface downwards on which lie the sections. 



For large sections it is best to use flat perforated porcelain 

 dishes ; in transferring from one fluid to another excess of fluid 

 is allowed to run off", and the dish with the sections is then 

 placed on thick blotting-paper to drain. When the sections are 

 staining they should be moved now and then with a brush. 



B. Albumin fixative for sections. 



White of egg 50 c.c. 

 Glycerine 50 c.c. 



Salicylate of soda 1 grm. 

 Shake up well and filter. The fluid filters very slowly. 



Shellac. Dissolve pieces in creosote in the warm ; if 

 necessary filter warm. 



Collodion. Make a thin solution of collodion or celloidin in 

 clove oil. 



C. The distinctness of the different constituents of a section 

 depends in part upon the refractive index of the substance in 

 which the section is mounted. Generally speaking fluids of low 

 refractive index are advantageous when the parts to be seen are 

 not deeply stained. The following are arranged in order of 

 increasing refractive index ; 



(1) water, (2) 2 p.c. sodium chloride, (3) 90 p.c. alcohol. 



