CHAPTER XXX. 389 



dyes are a failure, This author believes that blood cells behave towards 

 these dyes just as they do to any foreign matter. Other authors do not 

 agree. " To dismiss these cells (pyrrhol cells) as scavengers is to do them 

 an injustice, for, however important this function may be, their service 

 to the body is a far greater one " (P. Gr. SHIPLEY, Amer. Journ. Physiol., 

 xlix, 1919, p. 300). 



EVANS and SCHULEMANN (Science, N.S., 1914), believe that vital 

 staining with azo dyes is the result of " phagocytosis " of ultra-micro- 

 scopic dye particles, existing in a state of fine dispersion as an hydrosol. 

 In using the term " phagocytosis " Evans does not quite mean an 

 engulfing by pseudopodia as with amoeba. P. G-. SHIPLEY (Amer. 

 Journ. Physiol., 1919, p. 285) points out that some cells which are 

 most active in phagocytosing bacteria and other coarse particles, take 

 no part, under ordinary conditions, in the segregation of vital dyes in 

 the body of the living animal. 



It has been stated that the benzidine dyes are not characterised by 

 a propensity for staining the mitochondria, as are Janus green or 

 dahlia. The granules in cells which store ultramicroscopic particles of 

 the benzidine dyes seem to be something apart from the mitochondria. 

 Only occasionally the mitochondria, as such, take up a benzidine dye 

 like trypan blue. In tissue cultures from forty to sixty hours old 

 many of the cells are seen to contain large greyish granules which were 

 either not present in the early stages or were not very noticeable. Such 

 granules (" segregation granules " of Shipley, and possibly degeneration 

 or "neutral red" granules of the Lewises, Amer. Journ. Anat., 1915), 

 stain red in neutral red and deep purple in cresyl blue, and by using 

 a combination of trypan red and Janus green, it can be shown, according 

 to Shipley, that the mitochondria (green in the Janus) and the segrega- 

 tion granules which take up the azo red dye, are separate entities. 

 This opinion is not shared by TSCHASKIN (Fol. Hcern., 1914), by LEVY 

 (E. Accad. d. Lincei, 1916), and by MAXIMOW (Arch. Euss. d'Anat. 

 d. Hist, et d'Embryol., 1916). 



Trypan blue is also used for demonstrating areas of osteoblastic 

 activity (Shipley and Macklin). See 780. 



The Methods of using Benzidine Dyes are as follows : Trypan blue 

 and pyrrol-blue of 1 per cent, strength in Ringer's solution are 

 injected subcutaneously, intraperitoneally or into the blood vessels. 

 Whereas 1 c.c. of a 1 per cent, solution per 20 grms. of the animal's 

 body weight injected subcutaneously has no ill-effect on the animal, 

 no more than 0-5 c.c. of the same solution should be used for intra- 

 vascular work. In the latter case coloration sets in speedily, 

 increases up to the second day, but rapidly fades after the fourth 

 day, in any case, quicker than when gradual absorption of the stain 

 takes place through the lymphatic channels. It is undoubtedly 

 safest and best for histological study to inject the staining fluids 

 subcutaneously. Injections of 1 c.c. of a 1 per cent, solution per 

 20 grms. body weight may be repeated many times once a week. 



