182 SERIAL SECTION MOUNTING. 



the next section is being cut, with the sections upwards 

 on a moist surface prepared by arranging several layers of 

 blotting paper, covered with one layer of closet paper, in a 

 plate, and saturating the whole with alcohol. When all the 

 sections have been arranged on the slip, you pass to the next 

 stage of the process, the collodionisation of the series. 



This is done in two steps. The first of these consists in 

 transporting the series on to a plate of glass prepared with 

 collodion. The plate is prepared beforehand by pouring on 

 to it collodion and causing it to spread out into a thin layer, 

 as photographers do, and allowing it to dry. (A number of 

 the plates may be prepared and kept indefinitely in stock ; 

 microscope slides will do for series of small sections.) Take 

 one of these plates ; lay the slip of paper with the sections 

 on the plate, the sections downwards ; press it down gently 

 and evenly, and the sections will adhere to the collodion, then 

 carefully remove the paper. (Do not place more than one or 

 at most two lines of sections on the same plate, for those first 

 placed run the risk of becoming dry whilst you are placing 

 the others.) This finishes the first stage of the collodionis- 

 ing process. 



Now remove with blotting-paper any excess of alcohol that 

 may remain on or around the sections, pour collodion over 

 them, and get it to spread in an even layer. As soon as this 

 layer is dry at the surface you may write any necessary indi- 

 cations on it with a small brush charged with methylen blue 

 (the colour will remain fast thoughout all subsequent manipu- 

 lations). 



The plate may now either be put away till wanted in 80 per 

 cent, alcohol, or may be brought into a staining fluid. Weigert 

 recommends his haematoxylin process (see 180), but other 

 watery stains may be used. The watery fluid causes the double 

 sheet of collodion to become detached from the glass, holding 

 the sections fast between its folds. It is then easy to stain, 

 wash, dehydrate, and mount in the usual way, merely taking 

 care not to use alcohol of more than 90 to 96 per cent, for 

 dehydration. Weigert recommends for clearing the above- 

 described mixture of xylol and carbolic acid ( 298). Both 

 the dehydration and the clearing take rather longer with the 

 collodionised series than with free sections. 



The series should be cut into the desired lengths for 



