CURTIS' SUBSTITUTE 



76 



DAVENPORT'S 



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 heavj^ 

 staining with red is less likely. In 

 original account volumes are given in 

 ml. which are of practically the same 

 value as cc. 



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., 19i2, 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 less each. For 

 pieces more than 3 mm. 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 

 Keihn (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 

 is oxidized by cytochrome — oxidase 

 which is identical with indophenol 

 oxidase and Warburg's respiratory en- 

 zyme. See study of cytochrome 

 oxidase-cytochrome system in kidney 

 (Flexner, L. B., J. Biol. Chem., 1939, 

 131, 703-711). See Oxidase. 



Cytcphaga 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 Kurloff 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. 



Dahlia, see Hofmann's Violet. 



Dahlia B, see Methyl Violet. 



Damar is gum damar dissolved in xylol 

 and used to mount sections. 



Dark Brown Salt R, see Chrysoidin Y. 



Darkfleld Microscope. This is constructed 

 on the same principle as that of the 

 uUramicroscope developed more than a 

 generation ago by Siedentopf and Zsig- 

 mondy in so far that it depends on the 

 Faraday-Tyndall phenomenon of the 

 illumination of minute particles by light 

 reflected from their surfaces as when 

 tobacco smoke drifts into a beam of 

 light in an otherwise darkened room. 

 In the old ultramicroscope (intended 

 mainly for colloidal suspensions) the 

 illumination v.'as from one side through 

 a slit, while in the modern darkfield 

 condenser (designed for work with 

 cells) it is from below at the sides. 

 Ordinary oculars and low power ob- 

 jectives can be employed but for oil 

 immersion work the best objective is a 

 3 mm. fitted with an iris diaphram. 

 Especially adapted and more powerful 

 objectives can usually be obtained and 

 are of great value. Examination in the 

 darkfield is required for the study of 

 Microincineration preparations, of 

 living Spirochetes and other small 

 microorganisms, of Chylomicrons and a 

 wide variety of cellular components. 

 Ordinarilj'- the full usefulness of the 

 method is not realized because investiga- 

 tors content themselves with inade- 

 quate light and dry, low power, ob- 

 jectives. 



Davenport's 2-hour method for staining 

 nerve fibers in paraffin sections with 



