SPECIAL PROPERTIES OF THE PRINCIPAL TOXINS 117 



tralizing it, and characterized by its stability. The toxophore group 

 being destroyed as in old toxin, the poison loses its toxic qualities, birt 

 retains its power to bind antitoxin. This modified toxin or non-poisonous 

 diphtheria toxin has been designated by Ehrlich "diphtheria toxoid." 



2. Tetanus Toxin. Of all bacteria classed as true toxin producers, 

 none possesses greater toxicity than does the tetanus bacillus. The 

 number of organisms producing sufficient toxin to cause a fatal infection 

 may be so small that careful anaerobic cultures made from the local 

 lesion of infection, together with injection of the wound secretions into 

 white mice, may fail to disclose the presence of tetanus bacilli. 



According to Ehrlich, tetanus toxin is composed of two separate and 

 distinct substances (1) Tetanospasmin, a neurotoxin, which is very 

 labile and responsible for the severe symptoms of the infection; (2) 

 tetanolysin, a hemotoxin, which is more stable and destructive for ery- 

 throcytes. 



Tetanus toxin is prepared by cultivating the bacillus in bouillon 

 under strict anaerobic conditions. Since tetanospasmin is so suscep- 

 tible to the influence of heat, age, and even light, the toxin is best pre- 

 served in a dry form. The standard of tetanus toxin consists of 100 

 minimal lethal doses of a precipitated and dried toxin, preserved at the 

 Hygienic Laboratory of the Public Health and Marine-Hospital Service. 



If susceptible animals, such as mice or guinea-pigs, are injected sub- 

 cutaneously or intravenously with tetanus toxin, they begin to manifest 

 symptoms after a certain period; these are due to the action of tetano- 

 spasmin upon motor nerve-cells, and are characterized by hyper- 

 sensitiveness, clonic convulsions, and rigidity of the muscles. In man 

 the symptoms of tetanus are similar to those in the animal, the spasm 

 starting quite regularly in the muscles of the lower jaw. 



Experiments by Wassermann and Takaki have demonstrated that 

 an especially close affinity exists between tetanus toxin and certain 

 structures, particularly that of the central nervous system. Most 

 writers agree that the toxin reaches these tissues largely by way of the 

 nerve-paths. 



3. Botulism Toxin. This poison is generated by the Bacillus bot- 

 ulinus, first isolated, by Van Ermengem in 1896, from a ham during an 

 epidemic of meat poisoning. It is the cause of a type of meat and sau- 

 sage poisoning called botulism, more frequent in those countries where 

 raw meat is eaten, and frequently confused with "ptomain poisoning." 



The bacillus is a motile, spore-forming, anaerobic bacterium, which 



