India Ink

INDIA INK (Chinese ink, chinesische Tusche, encre de Chine, Chinese ink, Indian ink), a black watercolor paint representing an especially fine soot obtained by burning wood or vegetable oils with a limited supply of air; it is molded with animal glue and camphor (as well as other admixtures) in the form of sticks, from which a suspension of fine carbon particles is obtained by trituration in water. Commercial liquid India ink (the best being from the firm Günther-Wagner) is an aqueous suspension of fine carbon particles mixed with a protective colloid (gelatin, gum arabic) and a disinfectant (carbolic acid). India ink is used: 1) as a component of injection masses and fluids for studying the course of fine blood and lymphatic vessels and lymphatic clefts; 2) for vital injections into serous cavities or tissues when studying the pathways of lymph flow in tissues; 3) for vital parenteral injections when studying the phagocytosis of small particles by cells of the reticulo-endothelial system and for its blockade (it is recommended to subject India ink to preliminary treatment to remove foreign impurities); 4) in bacteriological technique for the study of microorganisms by Burri's method; 5) in histological technique for marking glass slides and for numbering celloidin sections; 6) in ophthalmology for tattooing the cornea in cases of leukoma. After introduction into the blood, India ink particles accumulate only in the reticulo-endothelial system associated with blood capillaries (i.e., in the Kupffer cells of the liver and in the reticulo-endothelium of the bone marrow and spleen). When introduced into tissues, India ink precipitates in large masses at the site of injection, is gradually phagocytosed there by macrophages, and accumulates in the reticulo-endothelial system of regional lymph nodes without appearing in internal organs. When introduced into the abdominal cavity, India ink coagulates in it, is then phagocytosed mainly by the macrophages of the omentum, and also gradually passes into the thoracic cavity via lymphatic pathways through the diaphragm and mediastinum, accumulating only in small quantities in internal organs. India ink remains deposited in tissues for a very long time within macrophages, which often take on the appearance of giant cells, and is eliminated from the body extremely slowly, mainly through the digestive and respiratory tracts.