FACTS REGARDING BACTERIAL TOXINS 195 



study of the effects produced by injecting into- animals either 

 the bodies of bacteria (killed by chloroform vapour or by heat) 

 or bacterial protoplasm disintegrated mechanically or artificially 

 autolysed. When effects are produced by such injections they 

 do not present in any particular case specific characters. They 

 usually appear very soon, it may be in a few hours after 

 injection of the toxic material ; there is not the definite period 

 of incubation which with other toxins often elapses before 

 symptoms appear. 



In certain cases there is difficulty in understanding the action 

 of bacteria which neither form soluble toxins in a fluid medium 

 nor possess a highly toxic protoplasm, and yet with which we 

 often see effects produced at a distance from the focus of 

 infection, e.g., b. anthracis. To explain such occurrences it has 

 long been regarded as a possibility that some bacteria are 

 only capable of producing toxins within the animal tissues, 

 and it has further been thought possible that bacteria, such as, 

 for example, the typhoid bacillus, which do distribute into 

 media intracellular toxins, might either produce these toxins 

 more readily in the tissues or might produce in addition other 

 toxins of a different nature. During recent years such toxins 

 have been much studied, and the name aggressins has been 

 given to them. The evidence adduced for the existence of 

 these aggressins as a separate group of bacterial poisons is of 

 the following kind : An animal is killed by a dose of the 

 typhoid, dysentery, cholera, or tubercle bacillus, or by a staphy- 

 lococcus, the organism being introduced into one of the serous 

 cavities. After death the serous exudation, which in all these 

 cases is present, is taken, and centrifugalised to remove the 

 bacteria so far as this can be done by such a procedure ; the 

 bacteria which are left are killed by shaking the fluid up with 

 toluol and leaving it to stand for some days. Such a fluid in 

 a dose which by itself has no pathogenic effect, has the property 

 of transforming a non-lethal dose of the bacterium used into one 

 having fatal effect. Further, the effects of the combined actions 

 of the bacteria and aggressins are often of a much more acute 

 character than can be obtained with toxic products developed in 

 vitro. The effects produced by aggressins are attributed to a 

 paralysing action on the phagocytic functions of the leucocytes. 

 The subject is full of difficulties, and in the case of certain of 

 the organisms employed results similar to those attributed to 

 aggressin action have been observed with the fluid obtained by 

 macerating living cultures, the deduction being that in the 

 aggressins we are merely dealing with a particular type of intra- 



