TOXINS— TOXALBUMINS—PTOMAINS 7 



Proteins are albuminoid bodies which are contained in 

 the actual substance of the bacteria, and whose chief point 

 of difference from toxalbumins consists in their not being 

 decomposed by boiling, even if kept up for hours. They 

 were discovered by Nencki, and further studied byBuchner. 

 Proteins can be abundantly obtained by boiling pure 

 cultures of bacteria in their bouillon or mixed with water. 

 Koch's tuberculin. belongs to this group of substances. 



Toxins, when injected in small quantity into animals, 

 have the property of affording immunity from infection 

 with the corresponding bacterium. 



According to Brieger, the cultures or juice from the 

 tissue should be filtered by means of earthenware cells, so 

 as to free the liquid from living germs. The albuminoid 

 substances are then precipitated with ten times the quantity 

 of absolute alcohol, redissolved in dilute alcohol, and pre- 

 cipitated a second time with an alcoholic solution of cor- 

 rosive sublimate. The mercury is next removed by means 

 of sulphuretted hydrogen, the residue dissolved in water, 

 and again treated with sulphuretted hydrogen ; this process 

 having been several times repeated, the toxins are finally 

 precipitated from the aqueous solution by absolute alcohol. 



SchoU produced a toxopeptone from cultures of cholera- 

 bacilli in hens' eggs, without filtration, by the following 

 process : — The albumen liquefied by the bacteria was poured 

 into ten times its quantity of absolute alcohol, and the 

 precipitate washed with alcohol, digested with water, and 

 filtered. The aqueous solution was then repeatedly added 

 to ether and alcohol slightly acidulated with acetic acid, 

 decanted each time from the residue, and the latter re- 

 dissolved in water rendered alkaline, after which a final 

 addition to pure ether, which was then evaporated off, 

 resulted in the obtaining of the poisonous substance. 



To procure ptomains from the actual bacterial cells 



