166 



The Validity of the Microchemical Test for the Oxygen Place in 



Tissues. 



By Alan K Drury, B.A., Shuttleworth Student of Gonville and 



Caius College. 



(Communicated, with a Note, by W. B. Hardy, F.B.S. Beceived April 25, — 



Bead June 18, 1914.) 



(From the Physiological Laboratory, Cambridge.) 



In the last few years endeavours have been made to locate precisely 

 certain reactions known to occur in the living cell ; and much work has been 

 done especially on the reduction place, the oxygen place, and the position of 

 oxidases and peroxidases. 



The reaction relied upon to indicate the position is always one involving 

 a colour change ; as an example, Unna's* method of fixing the oxygen place 

 in the cell may be chosen. He uses for this purpose a solution of rongalit 

 white,f which is a solution of the leucobase of methylene blue kept in a state 

 of reduction by excess of rongalit. an adsorption product of formaldehyde 

 with sodium sulphite. This solution is not affected by air or by light, but is, 

 according to Unna, a test for active oxygen. He places the section in a 

 solution of rongalit white for one minute, then washes in a large volume of 

 water ; when, the reducer having been washed away, the tissue is able to 

 show its ability to oxidise, and all the tissue elements which are capable 

 of effecting an oxidation are blued owing to the oxidation of the methylene 

 white to methylene blue. 



Unna has noticed that it is possible to abolish the staining of the oxygen 

 place by rongalit white, by the action of heat, neutral salts, alcohol, phenol, 

 and other protoplasmic poisons, while an ordinary nuclear stain is not thus 

 affected. Also the intensity of staining can be altered by previous treat- 

 ment with alcohol, formalin, or gum, while the action of a nuclear stain is 

 unaltered. He, therefore, asserts that the stained portions of the tissue are 

 the oxygen places. 



It is to be noticed that these comparisons are made between a very complex 

 mixture, namely, rongalit white, and a simple solution of a dye, so that they 

 are of little value unless controlled by an exact determination of the influence 

 of the constituents of rongalit white on the absorption process. 



* " Die Reduktionsorte und Sauerstofforte des tierischen Gewebes," P. G. Unna, 

 ' Arch, fiir Mikr. Anat.,' vol. 78 (1911). 



t " Zur Chemie der Haut. 6. — Hautreagentien," Unna and Golodetz, 'Monatshefte f. 

 Prakt. Dermat.,' vol. 50, p. 451 (1910). 



