374 



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



required to produce retardation of clotting in vitro as compared with the 

 amount necessary to give this result in vivo. Thus the original views 

 of the non-specificity of the action of " peptone " on shed blood gained 

 general acceptance. 



The present authors find that when blood is shed into " peptone " 

 without precautions to preserve it from changes towards coagulation, as in 

 the earlier work, then anticoagulant action is absent, except when the 

 " peptone " is present in relatively large amount. The following experi- 

 ments show that different results are obtained when blood is shed through an 

 evenly paraffined cannula from an animal respiring air. 





5 - 



6. 



7. 



8. 



9. 



10. 



Percentage of " peptone " 

 in blood 



p.c. 

 0-3 



p.c. 

 -325 



p.c. 

 0-6 



p.c. 



1 -o 



p.c. 

 1 -o 



p.c. 

 3-5 



Coagulation times of con- 



/ // 



7 45 



i ii 



5 55 



/ // 



7 45 



7 45 



/ // 



5 55 



/ // 

 7 25 



trol blood 



11 45 



8 10 



11 45 



11 45 



8 10 



8 45 



Coagulation times of " pep- 



13 20 



45 20 



16 30 



14 45 



21 4 



? 



tone " blood 



16 40 



48 50 



20 10 



23 40 



23 40 



? 



Coagulation times of 



8 10 



6 5 



8 10 



8 10 



8 10 



6 5 



" water " blood 



10 15 



7 55 



10 15 



10 15 



10 15 



7 55 



Notes. 



1. " Water" blood is normal blood to which a xolume of water or in No. 6 of '9 per cent. 

 NaCI equal to that of the peptone has been added. 



2. The upper of the two coagulation times is that of "commencement," the lower that of 

 " completion" of clotting. 



3. The blood was arterial and was withdrawn into glass vessels through paraffined cannulse. 

 The animals were pithed and were breathing air only. 



4. The "peptone" in Experiment No. 6 was dissolved in p 9 percent, sodium chloride; in 

 all others in this series in distilled water. 



5. Eoom temperature was 13-14° C. 



6. The " peptone " blood in No. 10 remained fluid during the next day. 



Experiment No. 5 shows that blood withdrawn from the carotid of a cat 

 through a carefully paraffined cannula into a clean glass vessel, and there 

 mixed immediately with " peptone " dissolved in distilled water, exhibited 

 a distinct retardation of clotting. This delay amounted to 5 minutes 

 25 seconds in the time of commencement, and 4 minutes 55 seconds in the 

 time of completion of clotting ; the amount of " peptone " in the blood was 

 only - 3 per cent. As is seen from experiments 7, 8, 9, and 10 with greater 

 concentrations of " peptone," the inhibition of clotting increased. When 

 solution is effected in - 9 per cent, sodium chloride as in Experiment 

 No. 6, the inhibition of coagulation is still more marked. Thus with a 

 concentration of 0325 per cent, of "peptone" in the blood a delay of 

 39 minutes 25 seconds in the commencement of clotting was observed, while 



