114 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
parts of ether and alcohol, forms solution 2, and some of solution 2 
similarly treated forms solution 3. The preparation is j)laced for 24 hours 
or longer in each of these solutions successively. For consolidating 
the celloidin flat glass capsules are to be used. In these the objects are 
placed, and the capsules filled to the brim and covered over for some 
hours with a glass plate, in order that by preventing the surface from 
becoming hardened any air-bubbles may be allowed to escape. The 
glass plate is replaced in the course of some hours by a bell-jar, and 
in 6-24 hours, whenahardish film has formed upon the celloidin surface, 
the capsule is filled up with 75 per cent, spirit. In 24 hours the celloidin 
is fit for sectioning. From the glass capsule the pieces are cut out and 
stuck with a thick solution of celloidin on elder-pith. The celloidin 
block should be broader than high, and the under surface scratched 
with a needle. The elder-pith and celloidin are to be firmly pressed 
together, and then placed in 70 per cent, spirit. 
For cutting sections from these blocks the knife should be smeared 
with yellow vaseline, and during the act of sectioning moved as nearly 
parallel as possible. 
C4) Staining' and Injecting'. 
Benzoazurin and Benzopnrpurin Stains for Microscopical Pur- 
poses.^ — Dr. Martin emjToys benzoazurin in watery dilute solution. The 
sections are overstained (1-4 hours, according to thickness of section or 
strength of solution). The sections are then decolorized with spirit 
acidulated with 1/2-1 per cent, hydrochloric acid. If a nuclear stain be 
desired, this effect may be counted on if the section be withdrawn when 
the celloidin is blanched. If the tissue elements are also to be dyed, 
then the decolorizing action must be interrupted earlier. A beautiful 
blue nuclear stain is thus obtained, and this is quite as distinct and sharp 
as that from carmine or logwood. This pigment seems, from the author’s 
account, to be very useful for epithelial cells, where it brings out the 
nucleus and the contour of the cell, and also for most connective-tissue 
elements. 
This dye seems to possess two valuable properties. The first is 
that old si^irit-preparations are stainable with comparative ease ; this is 
very difficult with other pigments, especially logwood, and the second is 
that preparations containing picric acid are little or not at all affected. 
Benzo-purpurin seems to be most suitable for double staining with 
haematoxylin or benzoazurin. 
Hsematoxylin Staining.f — Dr. S. Apathy advises serial sections to 
be stained with a solution of 1 part hasmatoxylin crystals dissolved in 
100 parts 70 per cent, spirit. They are then to be transferred to 70 per 
cent. sj)irit, to which a few drops of a 5 per cent, aqueous solution of 
bichromate of potash have been added. The haematoxylin solution is 
allowed to act for 10 minutes ; the sections are then mopped up with 
blotting-paper and placed in the bichromate spirit in the dark for five 
to ten minutes, when they assume a bluish tinge, the celloidin remaining 
unstained. A double stain for differentiating the nervous and connective 
* Deutsche Zeitschr. f. Tliiermed. u, Vergleicb. PatlioL, xiv. (1889) pp. 420-2. 
t Zeitschr. f. Wiss. Mikr., vi. (1889) pp. 179-1. 
