Selected monographs.

Date:: 1888

Catalogue details

Licence: Public Domain Mark

Credit: Selected monographs. Source: Wellcome Collection.

37/440 (page 21)

soda. We are tlioreforo perfectly justified iu stating that our present metliodsare not sufficient for tlie detection of extremely minute quantities of albumen in tlie urine, and tliat tlierefore urine in whiclx no albumen can be found may yet contain traces of that substance. In the second place, it is more in accord- ance with, our other experiences and ideas to assume quan- titative oscillations of a function within physiological limits rather than qualitative changes. For example, still to confine ourselves to urine, we daily see that any one of its normal constituents may be excreted in quantities greater or less than the average, but it is a far rarer occurrence, if after all under physiological conditions, for an entirely new substance and one hitherto absent to appear in the urine, unless it or something from which it could be immediately derived, had been introduced into the blood. Indeed, when something of this kind takes place, i.e. when a substance previously unknown in normal urine is discovered therein, we are, a priori and with justice, disposed to assume that it is a normal constituent of the urine, but one which has hitherto escaped recognition, by reason of the minuteness of its quantity or because our methods of investigation were inadequate for its detection. Of late years numerous experiences of this character have been afforded by various constituents of the urine. I refer especially to two of them, viz. gi'ape sugar^ and oxalic acid, because they play in pathology a part similar to that of albumen. How much controversy has taken place as to whether these substances belong to the normal constituents of urine, or whether their occurrence is under all circumstances a morbid phenomenon ! Nowadays we know that they do occur normally in urine, but in such insignificant quantities that a large volume of urine and very delicate methods are required for their demonsti-ation ; and we also know that 1 According to the most recent investigations tlae reactions supposed to be due to the presence of sugar in the urine may depend upon glycuron acid. For our purposes, however, this question is of no consequence, for sugar is referred to here only for the sake of comparison, and besides it and oxalic acid there are several other substances with regard to which the above statements equally hold good. These are hippuric acid, glycerin-phosphoric acid, inosite, xanthin, indoxyl-sulphate o£ potash (indican), phenol, pyro- catcchin, &c.