CYANOCHIN 



92 



DARK-FIELD MICROSCOPE 



running water. Stain 2-4 min. in Cur- 

 tis' substitute: 2% Ponceau S, CI, 282, 

 (National Aniline) 5 cc; sat. aq. picric 

 acid, 95 cc. ; 2% acetic acid, 2 cc. Rinse 

 in 96% alcohol, dehydrate, clear and 

 mount. Chromatin, black; cytoplasm, 

 yellow; collagen and reticular fibers, 

 red. Red and yellow colors are said 

 to be purer than those given by the 

 Van Gieson technique and too heavy 

 staining with red is less likely. In 

 original account volumes are given in 

 ml. which are of practically the same 

 value as cc. 



Cyanochln of Bresslau, E., Arch. f. Protis- 

 terik., 1921, 43, 467, see Cyanosine. 



Cyanosine, see Phloxine B. 



Cyclohexanone has been recommended for 

 dehydration and clearing instead of 

 absolute alcohol and xylol by Bourdon, 

 P., Bull. d'Hist. Appl., 1942, 19, 55. 

 After dehydrating tissue in 95% alco- 

 hol, 12 hrs.; pass to cyclohexanone, 

 4 hrs.; then to another lot of cyclo- 

 hexanone, 2 hrs.; and impregnate with 

 paraffin 2 baths 2 hrs. or le.ss each. For 

 pieces more than 3 nmi. thick longer 

 times are necessary. This saturated 

 cyclic ketone has density similar to 

 water, mixes with organic solvents and 

 paraffin and does not harden tissue. 

 From Review by Jean E. Conn in Stain 

 Techn. 



Cyclospora, see Coccidia. 



Cytocentrum, centrosome plus centrosphere. 



Cytochrome. This is the name given by 

 Keilin (D., Proc. Roy. Soc, 1925, B, 

 98, 312-339) to hemin compounds of a 

 reddish color which occur in oxidized 

 or reduced condition in almost all living 

 cells. Blaschko and Jacobson (Bourne, 

 p. 192) have summarized our knowledge 

 about them. They say that the red 

 color of cytochrome can be observed 

 when a slice of brain tissue, from which 

 the blood has been carefully washed out, 

 is suitably illuminated by transmitted 

 light. A thick suspension of yeast and 

 the thoracic muscles of insects are also 

 recommended as material. There are 

 4 cytochromes : a, b, c and as recog- 

 nizable spectroscopically. 



Cytochrome Oxidase. Cytochrome is ox- 

 idized by cytochrome — oxidase which is 

 identical with indophenol o.xidase and 

 Warburg's respiratory enzyme. See 

 study of cytochrome oxidase-cyto- 

 chrome system in kidne}^ (Flexner, L. 

 B., J. Biol. Chem., 1939, 131, 703-711). 

 See Oxidase. 



Cytolipochrome Pigment, see Lillie, p. 127. 



Cytophaga Group of organisms, enrichment 

 cultures, pure culture techniques, 

 methods of examination and identifica- 

 tion (Stanier, R. Y., Bact. Rev., 1942, 

 6, 143-197). 



Cytoplasmic Inclusions caused by viruses. 

 They are more diversified in size, shape 

 and chemical composition than the 

 Nuclear Inclusions. Frequently, as in 

 the case of large Negri Bodies, they 

 contain both acidophilic and basophilic 

 components (Trachoma Bodies). Gly- 

 cogen tests for Trachoma inclusion 

 bodies are described by Thygeson, P., 

 Am. J. Path., 1938, 14, 455-462. The 

 techniques mentioned for Nuclear In- 

 clusions may be employed. See de- 

 scription by Goodpasture, E. W. and 

 Woodruff, A. M., Am. J. Path., 1930, 

 6, 699-711 ; 713-720 of the reactions of 

 fowl-pox inclusions to potassium hy- 

 droxide and other chemicals and the 

 nature of the particles. See also Borrel, 

 Guarnieri and KurlofiT bodies. Rickett- 

 sia are not to be listed as cytoplasmic 

 inclusions but Giemsa's stain is the 

 best for them. 



In plant cells, as in animal ones, cer- 

 tain cytoplasmic inclusions are indica- 

 tive of virus action. They are of two 

 sorts: (1) X bodies, which are rather 

 amorphorus structures, and (2) crystal- 

 line inclusions. The latter are best 

 seen in the dark field and in polarized 

 light and are made up chiefly of virus. 

 For technique employed to demonstrate 

 the relationship of virus to inclusion 

 and a critical review of the whole prob- 

 lem of plant viruses, see Bawden, F. C. 

 Plant Virus Diseases, Waltham: 

 Chronica Botanica Co., 1943, 294 pp. 



Cytosiderin Pigment, Lillie, p. 127. 



Dahlia, see Hofmann's Violet. 



Dahlia B, see Methyl Violet. 



Damar is gum damar dissolved in xylol 

 and used to mount sections. 



D'Antoni's Iodine solution. First make 

 standardized 10% aq. potassium iodide. 

 Adjust by specific gravity method to 

 exact 10% concentration. To 100 cc. 

 of 1% aq. potassium iodide made from 

 it add 1.5 gm. powdered iodine crystals. 

 Allow to stand for 4 days before using. 

 Recommended for staining intestinal 

 protozoa (D'Antoni, J. S., Am. J. Trop. 

 Med., 1937, 17, 79-84). See McClung, 

 1950, p. 450. 



Dark Brown Salt R, see Chrysoidin Y. 



Dark-Field Microscope (From account in 

 Cowdry's Histology, 1950). In dark- 

 field microscopy the light comes in at 

 an angle, and does not enter the ob- 

 jective lens at all. It may be thought 

 of as oblique illumination carried to the 

 limit of obliquity. If there is nothing 

 in the field of view the background will 

 of course be perfectly dark; but the 

 presence of objects will result in the 

 reflection of some light laterally into 

 the objective lens. Since only a minute 

 fraction of- the illumieation beam of 



