TECHNIC (BLOOD AND BLOOD-FORMING ORGANS). 227 



with a solution of equal parts of alcohol and ether for from one to twenty- 

 four hours, after which they are again dried in the air, and are then ready 

 for further treatment. 



A cover-glass preparation of fresh blood may also be treated for a 

 quarter of an hour with a concentrated solution of corrosive sublimate in 

 saline solution, then washed with water, stained, dehydrated with alcohol 

 and mounted in Canada balsam. A concentrated aqueous solution of 

 picric acid may also be used, but in this case the specimen should remain 

 in it for from twelve to twenty-four hours. 



The elements of the blood may also be examined in sections. 

 Small vessels are ligated at both ends, removed, fixed with osmic acid, 

 corrosive sublimate, or picric acid, and imbedded in paraffin. 



After fixation by any of the above methods the blood-cells may 

 be stained. Eosin brings out very well the hemoglobin in the blood- 

 cells, coloring it a brilliant red ; the stain should be used in very dilute 

 aqueous or alcoholic solutions (i% or less), or in combination with alum 

 (eosin i gm., alum i gm., and absolute alcohol 200 c.c., E. Fischer). 

 Eosin may also be used as a counterstain subsequent to a nuclear stain 

 for instance, hematoxyiin. The preparation is stained for about ten min- 

 utes, then washed in water or placed in alcohol until the blood-cells alone 

 remain colored ; the cover-glass preparation should then be thoroughly 

 dried between filter-paper and mounted in Canada balsam. Besides 

 eosin, other acid stains as orange G, indulin, and nigrosin have the 

 property of coloring blood-cells containing hemoglobin. 



Blood platelets are best fixed with osmic acid, and may be seen 

 without staining. They may also be stained and preserved in a sodium 

 chlorid solution to which methyl-violet is added in a proportion of 

 i : 20000 (Bizzozero, 82). Afanassiew adds 0.6% of dry peptone to 

 the solution (this fluid must be sterilized before using). 



Ehrlich's Granulations. The leucocytes of the circulating blood 

 and those found in certain organs possess granulations which were first 

 studied by Ehrlich and his pupils, and which may be demonstrated by 

 certain methods. The names given to these granulations are based upon 

 Ehrlich's classification of the anilin stains, which differs from that of the 

 chemist. This author distinguishes acid, basic, and neutral stains. By 

 the acid stains he understands those combinations in which the acid is the 

 active staining principle, as in the case of the picrate of ammonia. 

 Among these are congo, eosin, orange G, indulin, and nigrosin. The 

 basic stains are those which, like the acetate of rosanilin, consist of a 

 color base and an indifferent acid. To these belong fuchsin, Bismarck 

 brown, safranin, gentian, dahlia, methyl-violet, methylene-blue, and tolui- 

 din. Finally, the neutral anilins may be considered as those stains which, 

 like the picrate of rosanilin, are formed by the union of a color base with 

 a color acid. The granula may be demonstrated in dry preparations as 

 well as in those fixed with alcohol, corrosive sublimate, glacial acetic acid, 

 and sometimes even Flemming's solution. Five kinds of granules are 

 distinguished, and designated by the Greek letters from alpha to epsilon. 



The a-granules (acidophile, eosinophile) occur in leucocytes 

 of the normal blood, in the lymph, and in the tissues, and are differen- 

 tiated from the others by their peculiar staining reaction to all acid stains. 

 They are first treated for some hours with a saturated solution of an acid 



