56 BACTERIAL POISONS. 



mass of this extract consisted of fats and fatty acids, and 

 for some weeks I endeavored to extract the poison from 

 these fats, but all attempts were unsuccessful. I then made 

 an aqueous extract of the cheese, filtered this, and drinking 

 some of it, found that it also was poisonous. But after 

 evaporating the aqueous extract to dry ness on the water- 

 bath at 100, the residue thus obtained was not poisonous. 

 From this I ascertained that the poison was decomposed or 

 volatilized at or below the boiling-point of water. I then 

 tried distillation at a low temperature, but by this the 

 poison seemed to be decomposed. 



" Finally, I made the clear, filtered aqueous extract, 

 which was highly acid, alkaline with sodium hydrate, agi- 

 tated this with ether, removed the ether, and allowed it to 

 evaporate spontaneously. The residue was highly poison- 

 ous. By re-solution in water and extraction with ether, the 

 poison was separated from foreign substances. As the ether 

 took up some water, this residue consisted of an aqueous 

 solution of the poison. After this was allowed to stand for 

 some hours in vacuo over sulphuric acid, the poison sepa- 

 rated in needle-shaped crystals. From some samples the 

 poisoned crystallized from the first evaporation of the ether, 

 and without standing in vacuo. This happened only when 

 the cheese contained a comparatively large amount of the 

 poison. Ordinarily, the microscope was necessary to detect 

 the crystalline shape. From sixteen kilogrammes of one 

 cheese, I obtained about 0.5 gramme of the poison, and in 

 this case the individual crystals were plainly visible to the 

 unaided eye. From the same amount of another cheese I 

 obtained only about 0.1 gramme, and the crystals in this 

 case were not so large. 1 have no idea, however, that by 

 the method used all the poison was separated from the 

 cheese." 



To this ptomaine VAUGHAN has given the name tyr<>- 

 toxicon (rvpos, cheese, and TO&KOV, poison). Its chemistry 

 will be discussed in a subsequent chapter. 



During 1887, WALLACE found tyrotoxicon in two 

 samples of cheese which had caused serious illness. The 

 first of these came from Jeanesville, Pa., and the symptoms 



