376 Drs. J. W. Pickering and J. A. Hewitt. 



disturbed conditions of the paraffined vessels is the continuous inhibitory 

 action of the " peptone " made evident. 



A comparison of the coagulation times of pure blood on paraffined 

 surfaces with those of blood mixed with " peptone " on similar surfaces 

 shows less relative retardation in the time of commencement of clotting 

 than is evident when the coagulation of pure and peptone blood in uncoated 

 vessels is compared. The relative retardation in the time of completion of 

 the clots is much more marked when blood mixed with " peptone " is in 

 paraffined vessels than when it is contained in glass vessels not so treated. 



In this connection, the partial failure of one experiment is noteworthy. 

 The blood contained 08 per cent, of "peptone." It did not commence to 

 clot until 31 minutes after the mixing of the blood and " peptone," but 

 coagulation was complete 2 minutes later, a firm clot being formed which 

 could be inverted without spilling. 



This is a marked contrast to Experiments 11, 12 and 13, and cannot be 

 ascribed to the higher concentration of " peptone " used, as typical slowing of 

 clotting has been obtained after the appearance of the first clot in a number 

 of cases where this and higher concentrations of " peptone " have been 

 employed. In the specific case referred to, examination of the vessel 

 containing the peptone blood revealed a small defect in the paraffin lining, 

 with adherent fibrils to the exposed glass. Clotting had started from this 

 point, and had spread through the liquid. 



Attention is drawn to Experiment 13, where the " peptone " was 

 0"6 per cent, of the mixture ; here clotting did not commence till 45 minutes 

 20 seconds, and was completed only as a semi-gel 2\ hours after mixing. 

 A small amount of the fluid was withdrawn by a pipette before coagulation 

 was complete, and carbon dioxide passed through it. Clotting was observed 

 after 10 minutes. This result was also obtained by dilution with distilled 

 water. Other observations gave similar results. During the progress of the 

 delayed clotting, portions of what remained fluid were, from time to time, 

 withdrawn, and mixed with one-fourth of their volume of saturated 

 ammonium sulphate. A precipitate of what was probably fibrinogen was 

 always obtained (McLean, 39), till, at the end of the coagulation process, 

 when the clots appeared to be complete, tests of the residual fluid yielded no 

 precipitate. The mixture of " peptone " and blood in vitro thus behaved 

 precisely as the blood peptonised in vivo. 



Sehmidt-Mulheim (loc. cit.) gives the dose of " peptone " necessary to 

 produce incoagulability of circulating blood of dogs as from 0*3 to 0'6 grm. 

 per kilogramme. Pollitzer (loc. cit.) found cats to be more resistant. Taking 

 an animal weighing 3 kgrm., it may be assumed to contain 200 c.c. of 



