Pathologist to The Bland-Sutton Institute, The Middlesex Hospital ; and M. HYNES, B.A., Demonstrator in Pathology, The Bland-Sutton Institute, The Middlesex Hospital.THE decreased resistance of the red corpuscles to relatively high concentrations of saline has long been known as an almost pathognomonic test for htemolytic icterus, whilst the wide application of the fragility test has shown that more information is given by a quantitative determination than by a simple qualitative test. But, except for Simmel (1923), no very detailed accounts of a quantitative technique have been published despite the fact that many authorities emphasise the value of such a method. The ordinary method is briefly thus. Withdraw some blood from a vein into a syringe containing 3.8 per cent. sodium citrate solution, taking 4 parts of blood to 1 part of the citrate. Wash the corpuscles three times in physiological saline and make a 1 in 100 dilution of the packed washed corpuscles in tubes containing concentrations of saline varying from 0.25 to 0.75 per cent. When hEmolysis occurs it is shown by a tinge imparted to the supernatant fluid whilst the degree of hzmolysis can be roughly estimated by comparing the tinges with the naked eye. Obviously the large personal error involved in this method makes the procedure unsuitable for accurate quantitative work.Simmel's technique was a great improvement but his work does not seem to have attracted much notice in this country. Simmel used, instead of saline solution, a solution of salts in the proportions in which they occur in human blood and having the same osmotic pressure as the blood plasma. Dilutions of the stock solution to 30, 40, 50, 60 and 70 per cent. in distilled water were made in order to estimate the fragility of the red cells.Simmel claimed two advantages for his method, firstly that the concentration of the various salts in the hypotonic solutions was proportional to the concentration in normal plasma, and secondly that the solution was well buffered and would therefore have a constant p H . The first point does not seem to us to be of great importance, for there can be no comparison between hEmolysis as 219
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.