104 THE ACUTE SELF-LIMITED INFECTIONS 



trouble in quarantine and reduces very greatly the number 

 of individuals who must receive an immunizing dose when 

 exposed to a case. It has been found possible also to immunize 

 Shick positive individuals by injecting mixtures of antitoxin 

 and toxin, the two being combined in such a manner that 

 the toxin is not at all dangerous. This procedure is espe- 

 cially valuable for nurses, doctors, and attendants in hos- 

 pitals or wards devoted to this disease. 



Pseudodiphtheria Bacilli. There is a group of organisms 

 called pseudodiphtheria bacilli, because of their resemblance 

 in morphology and growth to the true disease-producing 

 type. They are sometimes found in jaw abscesses or otitis 

 media. They do not produce the t pical diphtheritic sore- 

 throat. The presence of such forms in the throat often leads 

 to erroneous diagnoses and lengthens quarantine. Quar- 

 antine is demanded by health authorities until the throat is 

 shown to be clear of diphtheria bacilli. 



BACILLUS TETANI. 



Tetanus or lockjaw is a disease characterized by tonic 

 and clonic spasms of the muscles due to the effect of the 

 soluble poisons of the Bacillus tetani or tetanus bacillus upon 

 the central nervous system. This poison, like that of the 

 diphtheria germ, is separable or extracellular. It is produced 

 by the bacteria, absorbed along the motor nerves, and 

 carried to the brain and cord. Tetanus bacilli enter the body 

 almost invariably by punctured or lacerated wounds. They 

 multiply in the deep, covered position afforded by such 

 wounds, but are not themselves taken up by the blood to be 

 distributed throughout the body, only their poisons being 

 absorbed. The bacteria are common in soil, manure, dust 

 from covered places, wood and the like. Their vitality is 

 considerable, due to the formation of resistant spores. 



Wounds carry the germs beneath the skin, where they lie 

 covered and hidden in the deeper tissues. They do not grow 



