VITAL STAINING 331 



granules or vacuoles in their cytoplasm. Thus there is brought 

 about " an actual accumulation within the cell of vital dye- 

 stuffs in fluid, high-colloidal, flocculate or crystalline form " 

 (Evans and Scott, Contrib. to Embrij., x, 1921, p. 1). There 

 appears to be a protein substance associated with the dye droplets, 

 at least in advanced stages of segregation (Chlopix, Zeit. f. 

 Zellforsch., xi, 1930, p. 316). According to Schulemann {Biochem. 

 Zeit.. Ixxx. 1917, p. 1) the rate of diffusion of dyestuffs is the factor 

 which determines their suitability as vital dyes. Highly diffusible 

 dyes spread rapidly through the animal body, and are rapidly 

 excreted. Indiffusible dyes and colloids when injected sub- 

 cutaneously are deposited at the site of inoculation. The best 

 d\'estuffs for vital staining are those with medium rates of 

 diffusion. Both Schulemann {Biochem. Zeit., Ixxx, 1917, p. 1) 

 and VON Mollendorff [Ergeh. Physiol., xviii, 1920, p. 141) have 

 concluded that chemical constitution has no direct relation to vital 

 staining properties, but Cappell (J. Path, and Bad., xxxii, 1929, 

 p. 595) and Wallbach {Arch. f. expt. Zellforsch., x, 1931, p. 383) 

 do not agree with this conclusion. 



In addition to acid dyes, " vital staining " by segregation can 

 be brought about by other means, e.g. with colloidal metals 

 (collargol), india ink, and certain iron compounds. 



The segregation of acid dyes is a relatively slow process com- 

 pared with the staining of cell vacuoles by basic dyes. Further- 

 more, not all cells segregate acid dyes. Amongst those which 

 do are macrophages, fibroblasts, fat cells of the connective tissues, 

 Kiipffer cells and parenchyma cells of the liver, capillary epithe- 

 lium of the bone marrow and adrenal, reticulum cells of the 

 lymph nodes, thymus and spleen, and kidney epithelium cells. 



For further information concerning the cells which stain intra-vitam 

 with acid dyes see von Mollendorff {Abderhalden' s Hdb. biol. Arbeit- 

 smeth.. Sect. V., Part 2, 1921, p. 97), Glasunow {Zeit. f. Zellforsch, 

 vi, 1928, p. 773), Cappell (J. Path, and Bact., xxxii, 1929, p. 595), and 

 LuDFORD {Proc. R.S.B., civ, 1929, p. 4-9S, and ibid., cviii, 1931, p. 270). 



743. Staining of Cytoplasmic Bodies with Acid Dyes. Acid 

 dyestuffs rarely stain cytoplasmic inclusions, but instances have 

 been recorded : these include protein granules in epithelial cells 

 of the intestine of young mice, the secretion in mammary gland 

 cells, and in certain of the ductless glands (von Mollendorff 

 loc. cit., 1921) and granules (keratohyalin) in epidermal cells 

 growing in vitro (Ludford, 10th Sci. Rep. Imp. Cancer Res. Fd., 

 1932, p. 169). Staining of preformed inclusions in invertebrate 

 cells has been described by Chlopin {Arch. expt. Zellforsch., iv, 

 1927, p. 462). 



744. Staining of Preformed Structures with Basic Dyes. Accord- 

 ing to VON Mollendorff {Abderhalden'' s Hdb. biol. Arbeitsmeth., 

 Sect. V, Part 2, 1921, p. 97) the best basic dyes for staining cell 



