WEIGEKT'S COLLODION METHOD. 221 



held down by the vaselin). The series is then painted over 

 with some of the thickest celloidin solution used for imbed- 

 ding, 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 more 

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

 removed and brought for half an hour into 7-0 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. 



340. Weigert's Collodion Method (Zeit. f. wiss. Mik., 1885, 

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

 taken not to have so much alcohol on the knife as to cause 

 the sections to float. Prepare a slip of porous but tough 

 paper (Weigert recommends " closet paper"), of about twice 

 the width of the sections. Soak it in alcohol, take it by both 

 ends, stretch it slightly, and lower it on to the section that 

 is on the knife. The section will adhere to the paper, and is 

 taken up by moving the slip horizontally or slightly upwards, 

 away from the edge of the knife. Take up the first section 

 towards the end of the paper that you hold in your left hand, 

 and let the remaining sections follow in order from left to 

 right. After each section has been taken up, the slip is 

 placed, whilst 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 ; 



