476 SUMMARY OF CURRENT RESEARCHES RELATING TO 



quantity equal to that of the alum used ; of the latter, as much as the 

 hematoxylin. These additions impart to the ha^malum a red-violet 

 hue. The stained sections should be treated with tap-water to bring out 

 the blue. 



Both preparations can be obtained ready-made from Griibler, of 

 Leipzig. 



Modified Nocht's Stain for Blood Films.*— T. IV. Hastings gives 

 the following modification of Nocht's stain. Three solutions are re- 

 quired : (A) 1 p.c. eosin ; (B) 1 p.c. alkalin-methylen-blue ; (C) 1 p.c. 

 methylen-blue. B is prepared by adding to a warm 1 p.c. solution of 

 <lry sodium carbonate 1 p.c. of methylen-blue powder. The mixture 

 is heated over a water-bath for 15 minutes, and 30 c.cm. of water added 

 for each 100 c.cm. of original fluid to replace loss by evaporation. 

 After heating a second time over a water-bath for 15 minutes, the warm 

 alkalin-methylen-blue solution is poured off from the gummy residue, 

 partially neutralised with 5 to G c.cm. of 12*5 p.c. acetic acid, and 

 mixed with solutions A and C as follows : Distilled water, 1000 c.cm. ; 

 eosin solution A, 100 c.cm. ; alkalin-methylen-blue solution B, 200 c.cm. ; 

 methylen-blue solution C, until a fine precipitate forms (from about 

 70 to 80 c.cm.). This mixture of three solutions is allowed to stand 

 for ^ to 1 hour, filtered through one filter, the residue allowed to dry 

 in the air for 24 to 86 hours, and then dissolved in methylic alcohol. 

 About 0-3 grm. will dissolve 100 c.cm. of methylic alcohol, but must 

 be rubbed well in a mortar with pestle to obtain solution. 



To use the stain no fixation is required. The dried blood smears 

 are flooded with the staining solution for 1 minute ; the solution is 

 then diluted with distilled water (a few drops), and the diluted stain 

 allowed to act for 5 minutes. The specimen is then washed thoroughly 

 with distilled water and mounted in the usual way. 



Staining the Myelin in Sections of Nervous Tissue previously 

 treated by Marchi's Method.! — S. Ramon y Cajal recommends the 

 following procedure. Thin sections are first washed in distilled water, 

 and then placed for 24 hours in the following solution : Hydrochinon 

 4 grin., water 100 grm., glacial acetic acid 5 grm. After washing in 

 distilled water for a few seconds they are transferred to silver nitrate 

 solution : silver nitrate 1 grm., water 100 grm., ammonia 1 drop. 

 After 10 minutes the sections are re-transferred to the hydrochinon 

 solution for 2 to 5 minutes. After a rapid washing in distilled water 

 they are placed again in the silver bath for 5 to 10 minutes. On 

 removal they are again washed and then placed in a decolorising fluid, 

 composed of potassium ferricyanide 1 grm., water 100 grm., potassium 

 carbonate 0'5 grm. Herein they remain until the white substance has 

 assumed a pale brown hue (from 2 to 5 minutes). The sections are 

 then immersed for 2 to 5 minutes in a 12 p.c. solution of sodium hypo- 

 sulphite. After this the sections must be washed in several changes of 

 water, and then treated with 40 p.c. and absolute alcohol ; this last 

 step must be done rapidly in order not to damage the celloidin. They 

 aire then cleared up in bergamot oil and mounted in dammar. 



* John Hopkins Hosp. Bull, xv. (1904) pp. 122-3. 



t Trttbajos Lab. Investigacion biol. Madrid, ii. (1903) pp. 93-7. 



