I 

 58 MACFADYEN'S RESEARCHES 



secondary products of but little importance. Thus, in the case of 

 B. pyocyaneus it is possible to immunize an animal by cautious 

 injections of living organisms, yet its serum has no antitoxic 

 powers against the so-called toxin. 



These facts have turned attention to the bodies of the bacteria 

 themselves, with the result that they have been found to be 

 definitely toxic, although in many cases the toxicity is not great. 

 The theory has therefore been put forward by Pfeiffer espe- 

 cially that under normal circumstances these organisms do not 

 secrete a soluble toxin, but that their protoplasm itself is toxic, 

 and that it is only set free on the death and solution of the cell, 

 thus accounting for the slight toxicity of old cultures, in which 

 such a solution of the cells must take place. The symptom of 

 the disease caused by these organisms is attributed to the solu- 

 tion of the bacteria by the fluids of the body. 



The study of these endotoxins has not left the matter clear. 

 They are present in the bodies of the bacteria, whether the latter 

 have been killed by heat, by antiseptics, or by drying. They are 

 apparently but slightly soluble in water, but can be obtained in 

 solution by autolysis of the bacteria in normal saline solution in 

 the incubator, by grinding the dead bacilli, or by the use of very 

 high pressure (the method introduced by Buchner for the extrac- 

 tion of endo-enzymes from yeast). But it did not appear possible 

 to produce an antitoxin against this poisonous material ; in 

 addition, animals which have been immunized against the living 

 organism might be as susceptible as before to the dead bacteria, 

 or to extracts of them. 



The researches of Macfadyen and Rowland have apparently 

 disproved this, and tend to support the opinion that the endo- 

 toxin is a true toxin, for which an antitoxin can be obtained. 

 They obtained young cultures of various organisms, froze them 

 at the temperature of liquid air, and then ground them (whilst 

 solid) into an impalpable powder. This was made into a paste 

 with normal saline solution and centrifugalized, to remove any 

 solid particles. The juice thus obtained was sterile. It was 

 more powerful than endotoxins prepared in other ways, and it 

 acted very quickly, having a very short period of incubation, if 

 any. Thus, in the case of the typhoid toxin i c.c. killed in three 

 hours and -^ c.c. in less than two days, on intraperitoneal in- 

 jection. It was less active on subcutaneous injection not more 

 so, in fact, than other toxins of the typhoid bacillus requiring 



