1888.] MICROSCOPICAL JOURNAL. 131 



through. Then, after washing slightly in water, the}' are placed in a 1-50 

 or 1-100% solution of chromic acid 3 to 3 days in the dark, for the reduction of 

 the gold. Sometimes the reduction is not completed at the end of thistime, but 

 becomes so in the clearing and mounting in balsam. The more thoroughly 

 the chromic acid is washed out of the sections the sharper the pictures 

 will be. 



The non-medullated nerve fibres, to their finest ramifications, are stained 

 black ; the connective tissue cells stand "out shai'ply, the intercellular tissue 

 remains unstained. Striated and smooth muscle take a greenish shade. 



Carmine for staining in toto. E. Aievoli.* — To 100 c.c. of hot water 

 add I gm. of powdered carmine. When it has become diftused through the 

 water add 7 gms. of natrium phenatum. The mixture is kept at a moderate 

 heat for 30 to 40 minutes, with stirring, and then filtered. 



Bits of tissue are placed in this fluid for 20 to 24 hours, then in acidu- 

 lated (1%) alcohol for an hour. This gives an intense and clear nuclei 

 stain. 



Modification of Heidenhain's Haematoxylin Method. Stephan 

 Apathy. I — The author makes a 1% solution of hiematoxylin in 75 to So°o 

 alcohol and a solution of potassium bichromate of the same strength and in 

 the same medium. As the potassium bichromate is but slightly soluble in 

 alcohol he uses a 5% solution of this salt in water and dilutes i part of this 

 with 4 parts of So to 90% alcohol. The last solution is to be kept in the 

 dark, as in the light the chrome salts are precipitated. 



The time required for staining depends upon the size and penetrability of 

 the object. If the object be overstained with the hematoxylin, it will re- 

 quire a longer time for the action of the chrome salts. For thin sections 

 (10-15;/.) oi"^^ allows the chrome salts to act for half as long as the htema- 

 toxylin ; for thicker sections (25 to 40//) twice as long. The solution of 

 potassium bichromate should be renewed at least once. After the comple- 

 tion of the action of the chrome salt, the sections are washed in 70% alcohol, 

 which should be renewed several times, then placed in 90% alcohol and 

 finally in absolute alcohol. A good washing in alcohol, in the dark, for 

 many days prevents the precipitation of the salts in the tissues. 



Pyridine in Histology. De Souza.J — As pyridine, neutral in reaction, 

 coagulates albuminates it is a useful reagent for hardening animal tissues. 

 It is also miscible with oils, fats, and water, and ofi'ers certain advantages, 

 if the solution of the fat is not taken into consideration. 



In the warm oven it hardens small animals in eight days. The form is 

 well preserved, and at the same time the tissues are hardened, dehydrated 

 and cleared. After hardening the tissues cut easily and stain well with any 

 of the aniline dyes. The sections arc mounted in balsam, or after washing 

 in water they may be stained in picrocarmine or hojmatoxylin. 



Phenol in Microscopical Technique. A. Aievoli. § — To prevent the 

 rolling in cutting of paraflin imbedded objects various forms of section smooth- 

 ers have been devised. In order to do away with these the author advises 

 the following manipulation : — The parafiin imbedded object is cut and the sec- 

 tions allowed to roll up. They are then placed in benzine or turpentine for 

 3o minutes ; then they are transferred to pure phenol. In this the sections 

 unroll and float on the surface. 



Writing on Celloidin Blocks. Apathy, S.|| — Blocks of celloidin can 

 be labelled, if the characters are written, with a soft lead pencil on the bot- 



* Rivista Internaz. di Med. e Chinirg. Napoli, iv., pp. ic 

 t Zeitsch. f. Wiss. Mikros., v, 1888, p. 47. 

 tComptes rend. hebd. de la Soc. de Biol., iv, p, 622. 

 § Zeitsch. f. Wiss. Mikros., v. 1888, p. 66. 

 II Zeitsch. f. Wiss. Mikros., v. 1888, p. 46. 



