A contribution to the study of the yellow colouring matter of the urine / by Archibald E. Garrod ; [communicated by Sir Alfred B. Garrod].

  • Garrod, Archibald Edward, 1857-1936.
Date:
[1894]
Catalogue details

Licence: Public Domain Mark

Credit: A contribution to the study of the yellow colouring matter of the urine / by Archibald E. Garrod ; [communicated by Sir Alfred B. Garrod]. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    j v ■ J “A Contribution to the Study eu+the Yellow Colouring Matter of the Urine.” By i^Sctf'fBALD E. Garrod, M.A., M.D. Oxon., F,R.(X.IV.. £t$ai&ff^icated by Sir Alfred B. Garrod, M.D., F.R.S. Received February 5, 1894. Tlie uncertainty which still surrounds the origin of a phenomenon so familiar as the yellow coloration of the urine bears eloquent testimony to the difficulties which beset the investigation, by ordinary chemical methods, of such substances as the urinary pigments, and to the importance of the part which the spectroscope has played in the acquisition of such knowledge of them as we possess. Indeed, our acquaintance with the individual pigments is propor- tional to the distinctive character of their absorption spectra, rather than to the time which has elapsed since they first attracted atten- tion ; and in not a few modern works doubt is thrown upon the very existence of a distinct yellow pigment, having negative spectroscopic properties, but to which normal urine owes its characteristic tint, the chief part in the coloration of the excretion being assigned to urobilin. In this connexion the spectro-photometric researches of Vierordt* are of muck importance, for they appear to show conclusively that more than one pigment is present in normal urine. Vierordt found that with different specimens of the urine of a single healthy indi- vidual, examined at considerable intervals, the extinction coefficients for different parts of the spectrum exhibited relative as well as posi- tive differences. The variations of positive value are of course dependent upon the depth of colour of the specimen, bat the relative variations can only be explained by the presence, in varying proportions, of two or more distinct pigments. It must not, however, be forgotten that, as Vierordt himself points out, pigments which yield definite absorption bands may influence the extinction coefficients, even when present in such small quantities that their bands are not visible as such ; and it can be shown that at least three colouring matters, apart from a yellow pigment, may be present in any given specimen of the urine of a healthy individual, which may, nevertheless, exhibit no obvious selective absorption. Of these pigments, urobilin is certainly one, and when not seen on direct examination of the untreated normal urine, its band not in- frequently appears on standing, or on the addition of a mineral acid. Yet the quantity present is at best extremely minute, and wholly * ‘ Die Quantitative Spectralanalyse.’ Tubingen, 1876, p. 78. b