— 147— 

 flame. Tlie piece of tissue is placed in one end, and so 

 arranged that the phme in whicli it is to be cut, is at riglit 

 angles to the long axis of the trough. The paraffin is now 

 allowed to cool, and as soon as a film forms over it, the 

 trough is placed in cold water; this quickly congeals the 

 parafliii. The metalic L's are removed; the paraffin hlock 

 can now l)e taken from the glass |)late, and is read}'^ for cut- 

 ting. The knife used for cutting paraffin sections must he 

 dry, and if perfectly etuliedded very thin sections can be 

 cut, tliiiiner than when eniheddec], after any otlier metliod. 



Before mounting or staining paraffin sections it is 

 alwa3'S necessary to remove the paraffin. Before doing 

 this it is advisable to fix the section to the slide or cov(;r 

 glass by means of one of the many methods now in use. 

 Sections stuck to slide or cover can then be stained with- 

 out in the least destroying the relation of the elements of 

 the tissue. The contents 'of tubules, of small cysts or 

 spaces do not fall out during the process of staining and 

 mounting. 



Of the many methods used for fixing sections to slide 

 or cover glass, the following have been found by the author 

 to be most reliable. It must he remembered that sections 

 will not stick well unless the slide or cover glass is 

 thoroughly clean. In this laboratory they are cleaned by 

 placing the slides or cover glasses in strong sulphuric acid 

 for 10 to 15 minutes, then wash thoroughly in flowing 

 water, next place them for a few minutes in glacial acetic 

 acid, again wash in flowing water until all the acid has 

 been removed, pour off the water, and add 95% alcohol, 

 from which the slides or covers are wiped with a clean piece 

 of old linen. 



Albumen Fixative (Mayer). 



The albumen fixative consists of equal parts of white 

 of egg and glycerine. It is prepared by chopping the white 

 of an egg with a pair of scissors, then straining it through 

 muslin or linen ; it is now mixed with an equal quantity 

 of glycerine. The glycerine and white of egg are to be 

 thoroughly mixed by stirring with a glass rod, and filtered. 



