13 to 20.-Rocks from Wales, Stafford, and Salop. 21 21 or 26 22 1039 22 Olivine-basalt felspar) lage, (?)) Hornblende-schist Quarry near Church Cove, Lizard. .... 26 to 44.-Tertiary Rocks from Antrim. 45 from Down. Dolerite 0.00028 New quarry, back of railway station, 0.00229 0.00207 0.00218 The mean susceptibility of 1 to 12 (Northern Counties) is 20 (Welsh, &c.) ...... 21 25 (Devon and Cornwall) 26 45 (Antrim) Mean of 25 English rocks 20 Irish rocks.. Menn of all .. "On the Detection and Localisation of Phosphorus in Animal and Vegetable Tissues." By A. B. MACALLUM, AssociateProfessor of Physiology, University of Toronto. Communicated by Professor SHERRINGTON, 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 holding phosphorus which, ' under the microscope, gives as striking a demonstration of its presence as ferrous sulphide does of iron. Ammonium phosphomolybdate 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 precipitate may be in a much more finely divided form, the canaryyellow 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 Montit 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." 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." Raçiborski§ 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 à l'histoire biologique des phosphates," 'Comptes Rendus,' vol. 125, p. 538, 1897. "Ueber die mikro-chemischen Localisation des Phosphors in den Geweben," 'Zeit. für 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. molybdate occur, but a brown colour in other parts of an intensity which varies according to the length of time during which the preparation is washed, but if it is long and continuously treated with water no brown colour appears. The brown, therefore, would be due to molybdate of ammonium, and is no indication of the presence of the phosphorus compound. Heine was unable to confirm Raçiborski's observations regarding the reaction produced by pyrogallol, but he found, using stannous chloride as a reducing agent, that almost invariably a blue reaction appeared, which may pass eventually into a dirty green colour. In the test-tube also the reaction with the reducing agent is, according to the amount of the molybdate present, as well as to the strength of acidity in the fluid, a green, brown, or blue one, whether phosphates are present or not. Pollacci,† using zinc chloride as a reducing reagent, found the resulting colour range from dark blue to grey. It is evident from the foregoing that there is error somewhere in the observations which have been made on the action of pyrogallol on ammonium phospho-molybdate, and it is obvious that, if Raçiborski is right in his contention, then the results of the investigations of Lilienfeld and Monti, relying as they did upon the "yellow, brown, or black" reaction to indicate the presence of phosphorus, must be wrong. As a number of observers, including Sherrington, Gourlay,§ and Held,|| have used the same method and the same criteria on special tissue elements, it is therefore important to know the truth concerning the results so obtained. My observations confirm Raçiborski's on the action of pyrogallol on ammonium phospho-molybdate. When the former, in solution, aqueous or ethereal, is allowed to act on the thoroughly washed phospho-molybdate precipitate, the canary yellow of the latter is invariably turned to green, even in the presence of nitric acid, and this colour is maintained for a couple of hours, after which the precipitate takes up slowly a darker shade, until at the end of twenty-four hours it has a black colour with a faint shade of green in thin layers. The form of the crystals, which are black, is maintained. When the "Ueber die Molybdänsäure als mikroskopischer Reagens," 'Zeit. für Physiol. Chemie,' vol. 22, p. 132, 1896-97. 6 + "Sulla distribuzione del fosforo nei tessuti vegetali," Malpighia,' vol. 8, 1894; Abstract in 'Zeit. für Wiss. Mikrosk.,' vol. 11, p. 539. 6 "Note on some Changes in the Blood of the general Circulation consequent upon certain Inflammations of acute and local character," Roy. Soc. Proc.,' vol. 55, p. 161, 1894. 6 § "Proteids of the Thyroid and Spleen," Journ. of Physiol.,' vol. 16, p. 23, 1894. "Beiträge zur Structur der Nervenzellen und ihrer Fortsätze," Arch. für Anat. und Phys.,' Anat. Abthg., 1895, p. 396. |