FACTS REGARDING BACTERIAL TOXINS 189 



our chief knowledge concerning their effects is derived from the 

 study of what happens when the bodies of bacteria killed by 

 chloroform vapour or by heat are injected into animals. When 

 effects are produced by such injections they do not present in 

 any particular case specific characters. They are of the nature 

 !' u>'i irr;il disturbances of metabolism, as manifested by fever, 

 or by depression of temperature, loss of weight, etc., often of 

 such serious degree as to result in death. It is important to 

 note that when pathogenic effects are produced these 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 aygressins 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. It is stated that 

 such a fluid is of itself without pathogenic effect, but has the 

 property of transforming a non-lethal dose of the bacterium used 

 into one having fatal effect. Further, the effects of the com- 

 bined actions of the bacteria and aggressins are often of a much 

 more acute character than can be obtained with toxic products 

 developed in vitro. Thus, in the case of the action of a non- 

 lethal dose of the tubercle bacillus plus its aggressin, it is 

 >;ii I that death may occur in twenty hours, a result never 

 obtained with artificial cultures of the organism. The effects 



