316 TEXT-BOOK OF BACTERIOLOGY. 



older bouillon cultures of the bacilli (of a strongly-alkaline reaction) 

 possesses a very considerable degree of virulence. On injecting- it 

 into the subcutaneous cellular tissue or directly into the blood 

 current of rabbits, Guinea-pigs, and pigeons, it produces essen- 

 tially the same changes observed after inoculation with living 

 micro-organisms. Pseudo-membranes on the mucous surfaces do 

 not form in any case, but in connection with transmission paralyses 

 are developed which resemble those described above and are just as 

 fatal. Post-mortem examination after subcutaneous application 

 showed a hemorrhagic cedema of the abdominal walls and effusions 

 into the pleural cavity; after injection into the jugular vein, gener- 

 ally acute nephritis and a very pronounced fatty degeneration of 

 the liver are manifest. The greater the quantity of poisonous 

 fluid employed, the sooner the end will come ; but even very small 

 doses usually prove effective, except that the result may be delayed 

 for many days and even weeks. 



What is the nature and property of the toxic substance gen- 

 erated by the diphtheria bacilli ? Loftier, and afterward Roux 

 and Yersin, have attempted to answer this question, and believe 

 that we have here a body related to diastase or enzyme, since it 

 quickly decomposes and is destroyed at temperatures but little 

 above 55 C., is insoluble in alcohol, etc. 



Further investigations have shown that we have to deal with 

 an especially typical representative of the toxalbumins. On 

 evaporating some of the filtrate to one-third of its volume in a 

 vacuum at 40 C., and dropping it into absolute alcohol to which a 

 few drops of acetic acid have been added, a grayish- white, flaky 

 deposit is formed which sinks to the bottom in the course of a few 

 hours. This sediment is very soluble in water; it is precipitated 

 again by a new addition of alcohol. By repeating this procedure, 

 together with filtration and dialysis, it may be cleared of all ad- 

 mixtures so that, on drying it in a vacuum at 30 C., it will appear 

 as a snow-white amorphous and very light mass showing the most 

 important reactions of the albuminous bodies. It is at once decom- 

 posed by high temperatures and possesses highly- virulent proper- 

 ties. Even small doses give rise to the symptoms noticed after 

 injection of the filtrate; here too, the result is frequently retarded 

 for weeks. 



We have, then, presumably a direct derivative of the normal 

 tissue-albumin, which, decomposed by the bacteria in some par- 

 ticular manner, acquires a toxic power manifesting itself far and 

 near. We now understand why the rods in the pseudo-membranes 

 are only found on the surface, while the deeper parts (by the action 



