544 POWDERED DRUGS 



tine, it should be passed back and forth above the flame of an alcohol lamp. If 

 the sections are of a character not liable to shrink, they may be transferred directly 

 from water to the melted gelatine; if, however, there is danger of shrinking, the 

 sections should first be placed in a 10 per cent, solution of glycerine, which is then 

 allowed to concentrate by evaporation of the water, and then, from the concen- 

 trated glycerine the sections may be transferred to the drop of melted glycerine- 

 gelatine. To avoid air-bubbles the cover-glass should be put on with precau- 

 tion. If several sections are being mounted under one cover-glass, and these should 

 come to lie over each other in putting on the cover-glass, they may be properly 

 arranged without attempting to remove the cover-glass (which usually makes the 

 matter worse) by heating the slide until the gelatine becomes quite soft, and then 

 drawing a hair under the cover-glass, with which the sections may be manipulated. 

 It is sometimes a difficult matter to put just the right amount of the gelatine on 

 the slip. To overcome this difficulty, heat the gelatine and pour it out in a thin 

 film over a clean glass plate. When it has become cool, strip it from the glass; 

 then cut off small squares of different size, melt them separately on glass slips, 

 and cover with the cover-glasses of the size to be used with subsequent preparations. 

 The film of gelatine should then be cut into wafers of the size found to exactly fill 

 out the space under the cover-glass. These wafers should be kept from drying 

 too much and free from dust in tightly stoppered bottles. Specially valuable for 

 imbedding brittle objects. 



Gold Chloride. Protein crystalloids may be beautifully stained by means of a 

 solution of gold chloride. The material is to be fixed in a 20 per cent, solution of 

 corrosive sublimate in absolute alcohol, then the fixative is to be washed out in 

 alcohol containing iodine, and finally in pure alcohol; and then the sections are to 

 be placed in a i per cent, solution of gold chloride for about 3 hours. This process 

 is to be carried on in the dark. Then the sections are to be placed in a 5 per cent, 

 solution of formic acid, in which they are to remain for several hours exposed to 

 the light. They are next to be placed in 10 per cent, glycerine, which is allowed to 

 concentrate in a place free from dust, and from the concentrated glycerine they are 

 to be mounted in glycerine-gelatine, under which head will be found the method of 

 mounting. By this method of staining, the crystalloids are stained from rose to 

 violet. 



Gram's Method. This method is specially recommended for staining bacteria, 

 either in cover-glass preparations or in sections. The sections are stained in a 

 mixture of 100 mils of aniline water (prepared by combining about 5 mils of aniline 

 with 95 mils of distilled water), and II mils of a concentrated alcoholic solution of 

 gentian violet, or, better, methyl violet. This is filtered, and 10 mils of absolute 

 alcohol are added to it. The preparation is taken from the stain, rinsed in alcohol, 

 and transferred to a solution of 2 parts of potassium iodide, and I part of iodine in 

 300 parts of distilled water, where it remains from I to 3 minutes. Then it is 

 rinsed in alcohol, transferred to clove oil, and thence mounted in Canada balsam. 

 A good double stain is obtained if the clove oil has some eosin dissolved in it. 



Gunther's modification of the Gram method is as follows: The preparation is 

 stained and passed through the potassium iodide-iodine solution as above. Then 

 it is placed for i to 2 minutes in alcohol, next for 10 seconds in a 3 per cent, solution 

 of hydrochloric acid in alcohol, then again for several mirfutes in pure alcohol, until 

 no more color comes away, and then it is passed on into xylol, and finally is mounted 

 in Canada balsam. 



Greenacher's Borax Carmine. 



Carmine 3 g. 



Borax 4 g. 



Distilled water. . , . 100 mils. 



