300 A CHEMICO-PHYSIOLOGICAL STUDY OF 



substance. A second fall of blood-pressure, however, was not 

 prevented. Grosjean has pointed out that successive doses of 

 both proteoses and peptones produce successively a less marked 

 fall of arterial pressure, and a second or third injection may 

 even be without effect on this function, a condition attributed 

 to a degree of immunity acquired by the preliminary injection. 

 It is to be noted, however, that in Grosjean's experiments the 

 injections were undertaken at relatively brief intervals. 



In the preceding table are presented protocols from a few 

 of our own experiments bearing on the problem of peptone- 

 immunity. The data presented are somewhat incomplete and 

 fragmentary, still a few facts are clearly demonstrated. Thus 

 it is seen that the injection of active proteoses, such as pure 

 heteroalbumose or the mixed proteoses present in Witte's 

 " pepton," within an hour or two after injection of the sub- 

 stances enumerated in the table fails to develop the character- 

 istic clot-preventing power of the blood. There is to be sure 

 some slight retardation of coagulation, thus indicating that 

 the so-called immunity is by no means complete; but the 

 effect produced by the later injections is very slight indeed 

 as compared with the ordinary action of these products. 

 Experiments XX, XXII, XXIX, XV, and I, afford evidence 

 of the truth of this assertion. In other cases, as in Experi- 

 ments XVI and XXVI, the immunizing effect is manifested 

 by a delay in the appearance of retarded coagulation. Thus 

 in the two experiments just referred to, a considerable period 

 elapsed before the blood withdrawn from the vessels assumed 

 the characteristics of " peptone-blood." It would almost 

 seem as if the results indicated a deficiency of the clot-pre- 

 venting substances hi the body after the preliminary injection, 

 and that the latter are only slowly produced under the influ- 

 ence of the second injection. 



With reference to the effects of a second injection of pro- 

 teoses on arterial pressure our results clearly show that mean 

 arterial pressure is lowered somewhat by the second injection, 

 thus indicating that immunity hi this direction is by no means 

 complete. That the first injection, however, does give rise 



