66 THE AMERICAN MONTHLY [March, 



in the centre of the cell, so that a circle of air will surround it in the 

 finished mount. A coating of cement can be run on the cover glass 

 over the circle of air, so that it does not show, but gives the mount the 

 appearance of one with the cell full of glycerin. 



Notices of New Methods — VIII. 



By GEORGE C. FREEBORN, M. D. 



INSTRUCTOR IN NORMAL HISTOLOGY, COLLEGE OF PHYSCIANS AND SURGEONS, NEW YORK. 



Carmine Stains for Nerve Tissue. — Upson, H. S. — Neurol. Cen- 

 tralb., vii, 18S8, p. 391. 



I. One gramme of carmine is boiled for 20 minutes with 100 c.c. of 

 a 5% solution of alum ; this solution is allowed to cool and is then fil- 

 tered. To 5 c.c. of this solution add 10 to 20 drops of hydric acetate, 1 

 to 2 drops of phosphomolybdic acid and filter. Stain sections in this 

 fluid for 2 to 10 minutes, then wash well in water, dehydrate, clear and 

 mount in balsam. Axis cylinders, ganglionic cells and connective tis- 

 sue stain deeply ; nuclei stain faintly. 



II. To 5 c.c. of Grenadier's alum carmine add zinc sulphate to sat- 

 uration and then filter. Stain sections in this fluid for one-half to twelve 

 hours ; then wash well in water, .dehydrate, clear and mount in balsam. 

 Axis cylinders, the medullary sheath and Schwan's sheath are sharply 

 differentiated. 



Ill To a mixture of 4 c.c. of water and 1 c.c. of alcohol add 0.06 gm. 

 of carminic acid. Stain sections in this fluid for 3 to 10 minutes, then 

 wash in water and place in one of the decolorizing fluids given below. 

 The sections are to remain in the decolorizing fluid for 1 minute, they are 

 then removed, washed well in water and mounted in the usual manner 

 in balsam. The tint of the section depends upon the decolorizing fluid 

 used. Dilute hydric acetate gives a yellowish-red tint; saturated solu- 

 tion of lead acetate, blue ; ferrous sulphate, black ; manganese sulphate, 

 red : nickel sulphate or barium chloride, violet. Axis cylinders, gan- 

 glionic cells and connective tissue are stained. Nuclei do not stain 

 sharply. 



Nucina, a New Stain for Histological "Work. — Leon, Zool. 

 Anz., xi, 1S8S, p. 624. 



The author employs a coloring matter extracted from the green wal- 

 nut. It stains nuclei black ; also bacteria. He prepares the stain in 

 one of the following ways : 



a. Aqueous Extract. — The green walnuts are placed in a vessel and 

 covered with alcohol ; when the alcohol has become green, from the 

 dissolving out of the chlorophyl, they are removed and washed well in 

 water. Twenty-five walnuts are then placed in a porcelain dish with 

 coo c.c of water and boiled until the amount of water is reduced to one 

 half. This extract is then filtered several times through paper and the 

 filtrate boiled with 10% of alum. This fluid is used for staining. Its 

 action is less active than the alcoholic but the staining is more sharp. 



b. Alcoholic Extract. — After the green walnuts have been boiled for 

 a long time in water, the fluid is allowed to stand, when the Nucina 

 will be deposited. The water is poured off and 100 c.c of So% alcohol 

 for each 3 gms. of nuclei are added. The color of this solution is black 

 and is to be used for staining after adding a few drops of hydric chloride. 



