784 SUMMARY OF CURRENT RESEARCHES RELATING TO 



2. Dehydrate in pure acetone. On account of the great volatility of 

 acetone some care is necessary to prevent the drying of the preparation, 

 which should be avoided. 



3. Clear in pure oil of turpentine. 



4. Mount in a thick solution of colophonium in pure oil of turpentine. 

 Before mounting the preparation, the superfluous turpentine should be 

 carefully removed because this reagent rapidly takes up water from the 

 air, and thus may cause the clouding of the preparation or the fading of 

 the stain. 



The solution of colophonium is made by saturating a quantity of 

 turpentine with powdered colophonium, and keeping the filtered solution 

 in the paraffin imbedding oven until it has evaporated to the required 

 consistence. 



The use of acetone for dehydrating and of oil turpentine for clearing 

 and mounting is an important feature of the method, for these do not 

 destroy the characteristic staining of the granules in the giant cells and 

 platelets as do other similar reagents that have been tested. 



The staining fluid is composed of a mixture of 8 parts of a solution 

 of modified or polychromatized methylen-blue and 10 parts of a 0'2 

 solution of eosin, ^w.g.'" 1 (Grubler) in pure methyl-alcohol. It is per- 

 manent if kept in a well-stoppered bottle so that evaporation is prevented. 



The solution of methylen-blue is prepared as follows : One gram of 

 methylen-blue, B.X. (Grubler), is dissolved as thoroughly as possible 

 in 100 c.cm. of a 0*5 p.c. aqueous solution of sodium bi-carbonate in an 

 Ehrlenmeyer flask. The flask and its contents are then placed in an 

 ordinary steam sterilizer and kept at 100° C. for one hour and a half, 

 counting the time after the steaming has become vigorous. When cool, 

 the mixture is filtered, and the filtrate is the modified blue solution. It 

 must be of a well-marked purple colour when viewed in a thin layer by 

 the yellow transmitted light of an ordinary incandescent electric bulb. 

 This colour appears only after cooling. 



It is important that the quantities mentioned should be accurately 

 weighed or measured. An excess of eosin delays the appearance of the 

 scum on the surface of the diluted staining fluid, and the time required 

 for staining will be longer than ten minutes. On the other hand, au 

 excess of the modified blue component hastens the appearance of the 

 scum, and the staining may in ten minutes cause over-staining and the 

 granular precipitate to form on the preparation. 



The preparations should be viewed by the light from an incandescent 

 electric bulb which has a yellowish tint. This brings out more strongly 

 the characteristic colour of the granules in the megakaryocytes and in 

 the blood platelets. 



Staining Wet Films by Giemsa's Azur-eosin Method.* — G. Giemsa 

 fixes thin smears (malaria, trypanosomes, spirochastes, and such like) in 

 sublimate-alcohol (2 parts saturated aqueous sublimate solution and 

 1 part absolute alcohol) for 12 to 24 hours or longer, and then after a 

 short wash in water treats the preparation for 5 to 10 minutes in an 

 iodine solution (iodide of potassium 2 grm., distilled water 100 c.cm., 



* Deutsche Med. Wochenschr. (1909) p. 1751. 



