BACTERICIDAL SUBSTANCES IN FIBRIN. 173 



The experiments >vith a hemolytic serum derived from a rabbit that 

 had been immunized against bullock's blood corpuscles, showed, first, that 

 the addition of sterilized bullock's fibrin to the serum deprived the latter 

 of its specific dissolving power against bullock's blood and, secondly, that 

 this effect was due to the absorption of the immune body. 



In summing up the results of his investigations Kindborg assumes, 

 without any discussion, that the action of the fibrin in both sets of 

 experiments is identical. His conclusion, then, based upon the experi- 

 ments with the haBmolytic immune serum, is that fibrin possesses a 

 nonspecific power of absorbing the specific immune bodies. In all the 

 experiments, however, upon which this conclusion rests the fibrin used 

 was derived from the animal against whose blood corpuscles the immune 

 body was directed, so that its ability to unite with that substance can by 

 no means be regarded as nonspecific. It is not to be overlooked that 

 fibrin holds in its meshes the stromata of both red blood corpuscles and 

 blood platelets both of which possess a specific property of uniting with 

 the corresponding antibodies. 



Kindborg expresses surprise that Sieber should find bactericidal sub- 

 stances liberated by fibrin, whereas he himself has observed just the 

 opposite action of this substance — a prevention of bacteriolysis. The 

 explanation of this apparent contradiction is clear. Sieber subjected his 

 fibrin to a prolonged autolysis and tested the products of this process 

 directly upon the various microorganisms. Kindborg, on the other hand, 

 treated his fibrin for a considerably shorter time by a similar process and 

 exposed the much more sensitive complement to the injurious products. 



Kindborg also questions Ottolenghi's conclusions, arguing that in his 

 own experiments instead of a diminution of bactericidal property upon 

 the addition of fibrin an increase of this power, according to Ottolenglii, 

 must have resulted. To this argument Ottolenghi ^ replies that his 

 conclusions are applicable only to the case of anti-anthrax serum and its 

 special complement. 



From this brief review of the literature we see that the experiments of 

 Bergel are the only ones upon which the prospect for any practical use of 

 fibrin as a therapeutic agent can be based. 



In the course of some investigations carried out in the cancer institute 

 in Heidelberg, I took occasion to repeat some of the experiments described 

 by Bergel and by reason of the wide discrepancies between his results and 

 my own and in view of the practical significance of the matter, I have 

 thought it worth while to continue the study systematically. Part of this 

 work was done in the l)io]ogieal laboratory, Bui'eau of Science, Manila. 



In repeating Bergel's experiments the fibrin of rabbit and guinea pig 

 has been used, both from normal and immunized animals, and the sub- 



'Ibid. (1909), 49, 615. 



