396 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



between the fingers. The canula is now inserted in the mouth, and the 

 alimentary canal flushed out. When the stream runs clear, the animal 

 may be killed in some fixative solution. 



Fixing Intestine of Cat.* — Herr M. von Lenhossek states that he 

 has obtained brilliant pictures of the mucosa and musculature of the 

 intestine by the following method of fixing. A piece of intestine (small 

 intestine of cat) about 2 sq. cm. was stretched on a cork frame and fastened 

 down with quills, great care being taken to avoid touching the epithe- 

 lial layer. The preparation was then fixed in the following mixture : — 

 S bp-r^ Apathv's sublimate alcohol (alcohol 



FlG - 101 - 50 = 100 ccm., NaCl 0-5 grm., 



sublimate 4 grm.) 75 ; absolute alco- 

 hol 25 ; acetic acid 5 ; for 6 hours, 

 and afterwards hardened in 90 per 

 cent., 96 per cent., and absolute 

 alcohol for 24 hours each. 



Preparing Specimens of Iron 

 and Steel, t— Mr. W. M. Merrett 

 describes the following procedure 

 for preparing specimens of iron and 

 steel for microscopical observation. 

 Pieces 3/4 of an in. sqnare and 1/4 

 of an in. thick are taken, and one 

 surface is carefully ground on a 

 series of emery papers, mounted on 

 plate glass, finishing off with a 

 very fine grade. Fine-grade papers 

 are prepared by washing the finest 

 slime from the best flour emery, 

 mixing it with a solution of egg 

 albumen in water, brushing it on 

 paper free from grit, and then al- 

 lowing it to dry. The specimen is 

 rubbed on the fine emery paper, 

 then on rouge paper, and finally 

 on a wet rouge wheel. At this 

 stage the specimen becomes lightly 

 engraved, ■ the harder constituents 

 appearing in relief. The structure 

 is not shown by polishing only, but 

 must be made evident by physical 

 or chemical processes. The consti- 

 tuents are usually shown up either 

 (1) by rubbing the specimen with 

 liquorice juice on parchment ; (2) 

 by attacking it with a very dilute solution of nitric acid in alcohol 

 or in water; or (3) by heating it in air to about a straw colour 

 {240° C). 



* Auat. Anzei°r., xvi. (1899) pp. 334-42. 



f Illust. Ami. Microscopy, 1900, pp. 46-51 (12 figs). 



