Since lg97 when Vierordt published his method of estimating the coagulation time of the blood in man, eleven others have appeared. After working for some time with two of the more recent of them, I found that my results were discordant and unreliable.
I proceeded to a practical study of all the methods with the result that I came to the conclusion that there were certain essential conditions which required to be observed if accurate comparative results were to be achieved. None of the methods compliad with all these conditions and in particular they all failed to exclude the disturbing influence of slight temperature variations, and it is mainly on this account that the conclusions arrived at by different observers have been so contradictory.
I have succeeded in devising a method in which the temperature can be kept constant and in which the various other fallacies have to a great extent been avoided. By means of it I have been able to demonstrate the effect of different tempera- tures on the coagulation time and to show that the diurnal
diurnal variations in the time which have been differently described, in reality do not occur at all.
After showing that the administration of Calcium and Citric Acid produce alterations in the amount of ionisable Calcium in the blood, l have shown that nevertheless they have no appreciable effect on the coagulation time,