338 VITAL STAINING 



Okkels {Arch. f. exper. Zellforsch., viii, 1929, p. 432), Cappell 

 {loc. cit., 1929), Chlopin (Zeit.f. Zellforsch., xi, 1930, p. 316). and 

 Makarov {ihid., xix, 1933. p. 28). Saccharated oxide of iron is 

 regarded by Cappell as the most useful of all the suspensoids for 

 vital staining. He recommends a 10 per cent, solution by weight 

 in distilled water. This should be boiled to sterilise. 



Intravenous Injections. For mice, 0-3 c.c. of a 10 per cent, 

 solution to start with, and with later injections the amount can 

 be increased according to the tolerance of the animals. For 

 rabbits, 5 c.c. of a 25 per cent, solution by weight (Cappell, loc. cit., 

 1929). 



Fixation. Twenty per cent, formalin, or absolute alcohol. 

 Some workers employ a mixture of these two reagents. 



Demonstration of the Iron in Sections. Either the Prussian 

 blue reaction with potassium ferrocyanide and hydrochloric acid, 

 or the Turnbull blue method with ammonium sulphide followed 

 by acidulated potassium ferricyanide (see § 674). Sections can 

 then be stained with alum-carmine or para-carmine. 



PART III. VITAL STAINING WITH BASIC DYES 



759. Vital Staining of the Nucleus. There is a general consensus 

 of opinion that the nucelus does not stain under normal conditions 

 of metabolic activity, but some basic dyes, such as methylen 

 blue, stain nucleoli faintly, without killing the cells. According 

 to Russell {J. Expt. Med., xx, 1914, p. 545) gentian violet stains 

 the nucleus and chromosomes of embryonic and adult tissues of 

 the frog, in tissue cultures. He employed this dye in dilutions of 

 1 in 4,000 to 1 in 20,000 added to the culture medium. Staining 

 of the nucleus has been described under abnormal conditions of 

 metabolism, e.g. under anaerobic conditions, and also in a state of 

 acidosis (see § 746). 



760. Vital Staining of Mitochondria. Janus green is most 

 extensively employed for the vital staining of mitochondria. 

 According to Cowdry {Am. J. Anat., xix, 1916, p. 423) its action 

 depends upon the presence in its molecular structure of the 

 diethylsafranin group, and this alone is capable of staining 

 mitochondria. Other dyes containing the same group, and 

 possessing the same properties, are Janus blue, Janus black and 

 Janus grey. A good preparation of the dye is essential for the 

 best results. That of Hochster Farbewerke is generally recom- 

 mended. There is conflict of opinion as to whether mitochondria 

 can be stained with these dyes without cellular injury, but 

 Cow^DRY {Inter. Monatschr. Anat. Phys., xxxi, 1914, p. 267) 

 observed neutrophile leucocytes with vitally stained mito- 

 chondria performing amoeboid movements, and phagocytosing 

 foreign particles. The Janus dyes are employed in concentrations 

 of 1 in 10,000 to 1 in 500,000 in physiological saline. The latter 



