Stclair Thomson
1919 The Lancet  
689 From the data given it can only be deduced that the statement made by Douglas-that" the susceptibility of such cells to hasmolyt-in. although somewhat increased during the first 48 hours, subsequently appears to remain nearly constant for a greater length of time than that covered by our experiments "-is not in correspondence with the facts. This statement would indicate that the change in sensitiveness is rapid in the first 48 hours, and then becomes so slow as to be negligible. A study of
more » ... our table and diagrams shows that the change for the first two or three days is slower than on the subsequent days, and there is an indication that it becomes somewhat slower again in the later stages. In this connexion it is worth mentioning that a week or two after our last experiment the Rous-Turner suspension was found to show very marked spontaneous haemolysis in all bottles, though their contents were proved to be absolutely sterile. 80lntions of saponin. Before concluding a few further remarks may be made on the subject of saponin solutions. In Table II . there is presented an experiment which demonstrates the instability of saponin in dilute solution. Two precisely similar solutions (1/20,000), one fresh and the other five days old, were tested upon one and the same suspension of erythrocytes. It is seen that in three different doses the old solution is much less strongly haemolytic than the fresh. Similar tests were done on a number of occasions, and then always gave the same result. These findings furnish an admirable example of the truth that in all scientific work it is inadmissible to make assumptions as to the qualities (such as stability) of the materials employed. Suoh assumptions must be put to the test of experiment if the worker is to avoid the pitfall of false deduction. Conclusions. (1) By means of Rous and Turner's method it is not possible to obtain a standard suspension of red cells of constant sensitiveness to hsamolysins. (2) Therefore the use of such suspensions as a standard unchanging material for experimental work or for routine complement-fixation tests would necessarily lead to erroneous results. Nt)te -Since the completion of this paper an article by Dr. J W. Bisrger has appeared in the Journal of Pathology and Baoteriologil (May, 1919), nescribing furt her experiments on lines similar to those of Douglas and Bigger. In that article some observations are recorded which are in full agreement with our results, though a full inquiry into the question of the stability of Rous suspensions was not aftoft ont..
doi:10.1016/s0140-6736(01)48690-9 fatcat:n6q3l3vxd5gwnm7mydgjfygc5u