246 DEFENSE AGAINST NON-ANTIGENIC POISONS 



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 strychnine 

 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).^^ 



3^ Daniel, Jour. Exper. Zool., 1909 (6), 571. 



36 Arch. Internat. Pharmacoydn., 1910 (20), 393. 



