252 DEFEXSE AGAINST NOX-AyTIGEXIC POISONS 



glj'curoiiic acid, and acetic acid. .1/^ these substances are normally 

 present in the body, and none of them is specific against any one 

 poison, but each combines with several poisons. This last fact is 

 interesting in comparison with the highly specific nature of the im- 

 mune substances against bacteria and their products. 



As far as we know, no particular increase in the neutralizing sub- 

 stances results from the administration of inorganic or organic 

 poisons. The body does not appear to produce any excessive amounts 

 of sulphuric acid in carbolic-acid poisoning, or of glycocoll when 

 benzoic acid is administered. Both substances are present in the 

 body normally, and as much as is available combines with the poison ; 

 if there is not enough, the remaining poison combines with something 

 else, or goes uncombined. In other words, the neutralizing substances 

 described above do not appear to be the result of any special adapta- 

 tion to meet a pathological condition. They are present in the body 

 as a result of normal metabolism ; they have an affinity for various 

 chemical substances, some of w^hicli happen to be poisons ; if these 

 poisons happen to enter the body, they may be combined and neutral- 

 ized to some extent, but, as a rule, very incompletely. There appears 

 to be no elaborate process of defense against the chemically simple 

 poisons, such as seems to be called into action by bacterial infection, 

 and hence a degree of resistance or immunity similar to that present 

 after an attack of scarlet fever or smallpox does not exist for strychnin 

 or phosphorus. 



It is also of interest to consider that unicellular organisms may 

 show a marked capacity to increase their resistance to poisons, as 

 shown especially by Ehrlich's studies on trypanosomes, which readily 

 become immune to various trypanocidal drugs, including arsenic 

 compounds, and which transmit this acquired immunity through suc- 

 ceeding generations. Yeasts and bacteria can also exhibit increased 

 tolerance to antiseptics, and Effront found that yeasts owe their aug- 

 mented tolerance to fluorides to an increased content of calcium, 

 which precipitates the fluoride which enters the cells ; this tolerance is 

 also transmitted to new generations of yeasts. The acquired tolerance 

 is specific in all these cases, and may, indeed, be accompanied by 

 a decreased resistance to other poisons ; thus, protozoa acclimated to 

 alcohol may be more susceptible to other chemicals.-" Paramecia 

 made immune to antimony are not immune to arsenic, and this specific 

 immunity is transmitted to succeeding generations (Neuhaus).^" 



20 Daniel, .Jour. Exper. Zool., 1000 (fi), .571. 



30 Arch. Internat. Pliarmacoydn., 1910 (20), .303. 



