SERIAL SECTION MOUNTING. 149 



of the bergamot oil is exposed for a few minutes to the 

 vapour of a mixture of ether and alcohol, then brought into 

 90 per cent, alcohol,, and after a quarter of an hour therein 

 may be stained in any fluid that contains 70 per cent, alcohol 

 or more. 



If it be desired to stain in a watery fluid, care must have 

 been taken when arranging the sections to let the celloidin 

 of each section overlap that of its neighbours at the edges, 

 so that the ether vapour may fuse them all into one con- 

 tinuous plate. This will become detached from the slide in 

 watery fluids, and may then be treated as a single section. 



194. APATHY'S Series-on-the-Knife Method (////./. /**. 



vi, '2, 1888, p. 168). The knife is well smeared with yellow 

 vaselin rubbed evenly on with the finger, and is wetted with 

 alcohol of 70 to 90 per cent. As fast as the sections are 

 cut they are drawn with a needle or small brush to a dry 

 part of the blade, and there arranged in rows, the celloidin 

 of each section overlapping or at least touching that of its 

 neighbours. The rows are the length of the cover-glass, and 

 are arranged one under the other so as to form a square of 

 the size of the cover-glas<. When a series (or several series, 

 if you like) has been thus completed, the sections are dried 

 by laying blotting-paper on them (there is no risk of their 

 becoming attached to it, as they are held down by the 

 vaselin). The series is then painted over with some of the 

 thickest celloidin solution used for imbedding, is allowed to 

 evaporate for five minutes in the air, and is then either 

 wetted with 70 per cent, alcohol, and allowed to remain 

 whilst cutting is proceeded with, or (if no Tiiore sections are 

 to be cut, or if the knife is now full) the knife is removed 

 and brought for half an hour into 70 per cent, alcohol. 

 This hardens the celloidin around the sections into a con- 

 tinuous lamella, which can be easily detached by means of a 

 scalpel, and stained, or further treated as desired. It is well 

 to bring it at once on to a slide, moisten the edges of the 

 celloidin plate with ether and alcohol mixture, so that it may 

 not become detached, and bring the whole into the staining 

 solution. 



195. WEIGERT'S Collodion Method (Zeit. f. ids*. Mlk., 1885, 

 p. 490). Sections are cut wet with alcohol. Care should 



