COBALT NITRATE SILVER 



85 



COLLAGEN IC FIBERS 



fluenced by many factors. Small quan- 

 tities of many electrolytes cause coagu- 

 lation of colloids. Some ions are much 

 more powerful in this respect than 

 others and certain "protective col- 

 loids" such as gelatin protect colloidal 

 suspensions against coagulating action 

 of electrolj'tes. Peptization is dis- 

 integration of the coagulum into col- 

 loidal particles. Water is employed as 

 a peptizing agent in dissolving glue, 

 agar, and similar materials (Holmes, 

 H. N., Glasser's Medical Physics, 257- 

 263). 



Cobalt Nitrate Silver for Golgi Apparatus. 



Cocarboxylase, see Method of Westen- 

 brink, H. G. K., Enzymologia, 1940, 8, 

 97-107, capable of determining as little 

 as 0.01 fjL gm. of carboxylase. 



Coccidia. These sporozoa include many 

 parasites of great importance not only 

 to physicians and veterinarians but also 

 to cj'tologists who are interested in 

 their intracellular behavior. Conse- 

 quently the volume by Becker, E. R., 

 Coccidia and Coccidiosis of domesti- 

 cated, game and laboratory animals 

 and of man. Ames: Collegiate Press, 

 Inc., 1934, 147 pp. will contain numerous 

 helpful leads on the coccidia of the 

 digestive tracts of vertebrates and in- 

 vertebrates. See also McClung, 1950, 

 p. 455. 



Coccinel Red is 1, 5-diamylaminoanthra- 

 quinone, an oil soluble dye, recom- 

 mended by Lillie, R. D., Stain Techn., 

 1945, 20, 73-75 as a stain for fat which 

 it colors deep orange red. Make up 

 stock solution of 4.2% in absolute 

 (99%) isopropanol. Dilute this down 

 to 30 or 40% isopropanol with water and 

 treat frozen sections of normal cat kid- 

 ney and human adrenal with resulting 

 solution for 10-20 min. This solution 

 is only usable for several hours. Coc- 

 cinel red is a good counterstain after 

 hematoxylin. 



Coccinine (CI, 120), an acid monoazo dye, 

 light fastness 3 to 4, which colors sec- 

 tions pale pink not equal to Biebrich 

 Scarlet (Emig, p. 31). 



Cochineal (CI, 1239). This crimson dye 

 was in use by the Aztecs before the 

 Spanish conquest. It is derived from 

 an insect which feeds on a cactus. So 

 highly prized was it that Montezuma 

 took as yearly tribute from the State of 

 Huaxyacas (Now Oaxaca) 20 sacks of 

 cochineal. The invading Spaniards 

 were not slow to note the superiority of 

 cochineal over Kermes, the crimson 

 stain in use at home (1523 A.D.). 

 Charles V of Spain commanded Cortez 

 to inform him immediately "whether 

 what has been reported is true that 

 Kermes were to be found in abundance 



in New Spain and, if so, could be sent 

 with advantage to Spain". So coch- 

 ineal figured largely in the Aztec 

 tributes to Cortez and the industry 

 became a Spanish monopoly. In 1858 

 A.D. aniline red became a competitor, 

 depressed the sales of cochineal, which, 

 latter as a commercial dye, was defi- 

 nitely replaced when azo dyes came into 

 the market about A.D. 1880. (Leggett, 

 W. F., Ancient and Medieval Dyes. 

 Brooklyn: Chemical Publishing Co. 

 Inc., 1944, 95 pp.). See Kermes, Lac. 

 In microscopy cochineal is used 

 mostly for staining in tola of small in- 

 vertebrates. Mayer's alcoholic cochi- 

 neal is a popular preparation made, ac- 

 cording to Lee (p. 149), by powdering 

 5 gm. cochineal with 5 gm. calcium 

 chloride and 5 gm. aluminum chloride to 

 which 100 cc. 50% alcohol and 8 drops of 

 nitric acid (sp. gr. 1.20) are added. 

 Heat to boiling point, cool, shake oc- 

 casionally during several days and filter. 

 Before staining bring objects to 70% 

 alcohol, destain if necessary in 70% 

 alcohol containing 0.1% hydrochloric 

 acid. Dehydrate, clear and mount in 

 balsam. Nuclei are colored red and 

 other structures a variety of colors from 

 red to deep purple. In some respects 

 it is better than carmine. Neither fade. 



Cochlea, see Ear. 



Coelestin Blue, see Skyblue. 



Coeline, see Skyblue. 



Coeruleum, see Skyblue. 



Colchiceine, different from colchicine, see 

 Ludford, R. J., Arch. f. exper. Zellf., 

 1935-36, 18, 411-441. 



Colchicine, see Mitosis Counts. 



Collagenase. An enzyme which specifically 

 destroys collagenous fibers. Bidwell, 

 E. and W. E. van Heyningen, Biochem. 

 J., 1948, 42, 140-151, report on its isola- 

 tion and purification. 



Collagenic Fibers — Written by A. I. Lans- 

 ing, Dept. of Anatomy, Washington 

 University, St. Louis 10, Mo. October 

 5, 1951 — These are widely distributed in 

 the body, occur in large bundles in 

 tendons and are best viewed in spreads 

 of loose connective tissue. Unlike elas- 

 tic fibers which are yellow and highly 

 refractile, coUagenic fibers are white 

 and poorly refractile, form broad wavy 

 bands which do not branch, have great 

 tensile strength, and are attacked by 

 dilute acids and alkalis. On boiling 

 they yield gelatin. The fact that they 

 pass from the gel to the sol state on 

 alkalinization or warming is the basis 

 for methods of separating epidermis 

 from dermis. Collagenic fibers are 

 readily digested by pepsin in acid solu- 

 tion but resist trypsin. A specific col- 

 lagenase has as yet not been found. 



