INDIGO-CARMIN C. I. NO. I180 



Synonym: Indigotine la. 

 This is the sodium salt of indigodisulfonic acid : 



NaSOj CO CO SOjNa 



^rr \-/ ^rr 



\/\ / \ /\/ 



NH NH 



Indigo carmin is a blue dye of acid properties, which is sometimes 

 used as a plasma stain in contrast to carmin, either mixed with it 

 or following it.* 



Cochineal Products c. i. no. 1239 



Cochineal is a dye that has long been well known. It is obtained 

 from a tropical insect generally known as the cochineal insect. By 

 grinding and extracting the dried bodies of the female of the species 

 in question a deep red dye is obtained, which is known as cochineal. 

 By treating with alum this solution yields a product somewhat 

 more free from extraneous matter, known as carmin. This is the 

 form in which the dye is generalh^ obtained by the microscopist. 

 Cochineal products are used in various ways in microscopic technic, 

 generally as nuclear dyes. They are extremely valuable in cases 

 where it is desirable to stain in bulk before sectioning. 



Cochineal, itself, has been used for various purposes in micro- 

 scopic technic, even tho less used today than carmin. Alone it has 

 little value, to be sure, for it has no direct affinity for tissues unless 

 they contain iron, aluminium or some other metal. It is most 

 commonly employed either with or following one of these mordants. 

 A tincture of cochineal, that is an alcoholic solution containing 

 calcium and aluminium chlorides, has been used by Mayer both on 

 sections and for staining in bulk; but its most common method of 

 use is with alum in watery solution. An alum-cochineal of this 

 sort was first used independently by Mayer, Czokor, and Partsch; 

 it can be used for sections, and is specially recommended for stain- 

 ing in bulk, by which technic it stains nuclei violet red, and blood 

 and muscle cells orange, while the cytoplasm is but weakly colored. 

 A chrom-alum-cochineal has been used by Hansen for staining sec- 

 tions. Spuler recommends an iron-alum-cochineal for staining in 

 bulk when the sections are to be photographed, the technic bring- 

 ing out nuclei, the blood in the tissues, and the muscle striations; 

 sections may also be stained by the same method. By this technic 

 the iron alum is applied first to the tissues as a mordant, and then 

 followed by the stain. In Hansen's ferri-cochineal, on the other 



*For literature references to the procedures listed in this chapter see pp. 110 to 

 128 and 138 to 1-io. 



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