Detection and Localisation of Phosphorus in Tissues. 467 



" On the Detection and Localisation of Phosphorus in Animal 

 and Vegetable Tissues." By A. B. MACALLUM, Associate- 

 Professor of Physiology, University of Toronto. Com- 

 municated by Professor S HERRING TON, F.R.S. Received 

 June 15, Read June 16, 1898. 



The distribution of phosphorus, like that of organic iron, in tissues, 

 is a question of considerable importance to the cytologist and it is 

 therefore necessary that the method of detection for this element, 

 should be a satisfactory one. There are difficulties, however, which 

 make the micro- chemical detection of phosphorus less easy than in 

 the case of iron, for there is no precipitate hoi ding phosphorus which, 

 under the microscope, gives as striking a demonstration of its 

 presence as ferrous sulphide does of iron. Ammonium phospho- 

 molybdate is, in the test-tube, a markedly coloured precipitate, but 

 when its constituent crystals are examined under the microscope the 

 colour observed counts for little. When also, as in tissues, the pre- 

 cipitate may be in a much more finely divided form, the canary - 

 yellow colour may be so faint that it is indistinguishable from the 

 yellow produced in the tissue by the action of the nitric acid in the 

 precipitating reagent, although Jolly* holds that the yellow colour of 

 the phospho-molybdate compound in the tissue cannot be simulated 

 by dilute nitric acid. 



To get over these difficulties Lilienfeld and Montif used pyrogallol 

 to reduce the molybdic portion of the compound to the condition of a 

 lower oxide after they had, by washing the preparations in water, 

 removed the uncombined molybdate of ammonia from the tissues. 

 " Pyrogallol gives, in the test-tube with phospho-molybdic acid, an 

 intense colour varying from brown to black, whereby lower oxides of 

 molybdenum arise." J In speaking in another place of the action 

 of pyrogallol on the phospho-molybdate, they state that it gives, in 

 the parts of the preparations rich in phosphorus and according to 

 the quantity of the latter, " a yellow, brown, or black colour." 



Ra9iborski points out that the reaction of pyrogallol with 

 ammonium phospho-molybdate in the test-tube is a green one, while 

 that produced with ammonium molybdate is a brown one. This 

 author further states that the green reaction is obtained in the 

 tissues of Euphorbia wherever crystals of ammonium phospho- 



* "Contribution a 1'liistoire biologique des phosphates." 'Comptes Eendus,' 

 vol. 325, p. 538, 1897. 



tJ" Ueber die mikro-cheniischen Localisation des Phosphors -in den Geweben," 

 ' Zeit. fur Physiol. Chemie,' vol. 17, p. 410, 1893. 



Loc. cit., p. '411. 



Vide a criticism of Lilienfeld and Monti's observations,^ Bot. Zeit.,' vol. 51, 

 p. 245, 1893. 



