174 RELATIONS OF BACTERIA TO DISEASE. 



bacterium may be very complicated is shown by what is known 

 in the case of the vibrio cholerse, where the poisons which dis- 

 solve out into the culture fluid are quite different in their nature 

 from those which act when the dead bacteria are injected into 

 an animal. The extracellular toxins are the more easily obtain- 

 able in large quantities, and it is their nature and effects which 

 are best known. 



The Nature of Toxins. — Nearly all of what Httle is known 

 regarding this subject relates to the extracellular toxins. The 

 earlier investigations upon toxins suggested that analogies exist 

 between the modes of bacterial action and what takes place in 

 ordinary gastric digestion, and the idea has been worked out for 

 certain pathogenic bacteria by Sidney Martin. This observer 

 took, not solutions artificially made up with albumoses, but the 

 natural fluids of the body or definite solutions of albumins, and, 

 further, never subjected the results of the bacterial growth to 

 heat above 40°. C. or to any stronger agent than absolute 

 alcohol. He found that albumoses and sometimes peptones 

 were formed by the action of the pathogenic bacteria studied, 

 and further, that the precipitate containing these albumoses 

 was toxic. In certain cases the process of splitting up of the 

 albumins went further than in peptic digestion, and organic 

 bases or acids might be formed. According to Martin, the 

 characteristic symptoms of the diseases could be explained by 

 compound actions,; in-frwhich the albumoses were responsible 

 for some of the' effects, 'the other bodies for others. A simi- 

 lar digestive action has been traced in the case of the tubercle 

 bacillus by Kiihne. 



Further evidence that bacterial toxins are either albumoses 

 or bodies having a still smaller molecule is furnished by C. J. 

 Martin. This worker, by filling the pores of a Chamberland 

 bougie with gelatin, has obtained what is practically a strongly 

 supported colloid membrane through which dialysis can be made 

 to take place under the great pressure say of compressed oxy- 

 gen. He finds that in such an apparatus toxins, at least the two 

 kinds tried, will pass through just as an albumose will. 



Brieger and Boer, working with bouillon cultures of diphtheria 

 and tetanus, have, by precipitation with zinc chloride, separated 

 bodies which show characteristic toxic properties, but which have 

 the reactions neither of peptone, albumose, nor albuminate, and 



