88 



PRACTICAL HISTOLOGY. 



and clarified in watch-glasses, the sections being transferred from 

 one fluid to the other, and finally to the slide by means of a " lifter " 



(P. 3). 



Sometimes the one method is adopted, sometimes the other. 



To Clean a Microscopic Preparation. Any excess of balsam 

 round the edge of a preparation may be moved with a cloth dipped 

 in benzol. 



In the case of a preparation mounted in glycerine^ any excess of 

 the latter must be removed with great care, otherwise the cement 

 will not adhere to the glass. 



With preparations mounted in Farrant's solution, leave them in 

 an airy dry place for ten days or longer ; this gives the medium 

 time to harden at the edges, and fixes the cover-glass pretty firmly 

 to the slide. Place the slide in a basin of water, and with a 

 camel's-hair brush brush away from the edge of the cover-glass 

 every trace of the medium. There is no fear of disturbing the 

 cover-glass. Lave the slide in fresh water, and then wipe it 

 thoroughly dry. It is better to wash a number of slides at a 

 time. 



To cement or " Ring" the Specimens. 



Balsam Preparations need not be touched. They keep perfectly 

 without being covered in by coating the edge of the cover-glass 

 with an adhesive and resistant cement. If it be desired to cement 

 them, a thin coating of Hollis's glue must first be applied, and after 

 it is dry the cement is laid on as directed for preparations mounted 

 in Farrant's solution. 



To Ring a Slide. The slide should be fixed on a turntable, 

 the centre of the circular cover-glass corresponding to the centre of 

 the brass disc of the table. The slide is 

 fixed in position by means of two brass 

 clips (figs. 49, a, 1>, 50). 



For Farrant's preparations or (jlycerine 

 preparations, lay on a ring of white zinc 

 cement with a goafs-hair brush. The disc 



FIG. 49. Turntable for Ringing Slides. 



FIG. 50. Showing how slide 

 is to be centred on the 

 Turntable. 



is made to revolve with the fore-finger of the left hand, but not too 

 quickly, and a coating of the cement is laid on evenly. The fore- 

 finger is applied to the smaller disc (<}. 



