312 BACTERIOLOGY. 



nothing but the poisons modified by heating, 

 as some investigators have asserted. The 

 formation of both protective substance and 

 poison appears to be a " specific " activity of 

 certain species of micro-parasites. The at- 

 tenuation of disease-producing bacteria depends 

 accordingly upon the fact that the capacity for 

 forming poisons is diminished while other cell 

 activities are not essentially influenced. 



Proteids. 



Those proteid bodies which are obtained by 

 boiling bacterial cultures with and without ad- 

 dition of potash lye or of glycerine are certainly 

 not the substances" that bestow protection. 

 Whether the proteids obtained by this method 

 are produced from the real protective sub- 

 stances by the high temperature is still uncer- 

 tain. H. Buchner discovered that such pro- 

 teids provoke aseptic fever and inflammation, 

 and Hueppe and Scholl found also that they 

 act in characteristic ways, and cause leuco- 

 cytosis or local suppuration. Prudden and 

 Hodenpyl found that they act as a formative 

 stimulus to the body cells and Gartner and 

 Romer that they bring about lymph secretion. 

 In this category belong such substances as the 

 " tuberculin " obtained by Koch from tubercle 

 bacteria and the " mallein," obtained from cul- 



