360 AGEICULTUEAL AND INDUSTRIAL BACTERIOLOGY 



can, however, neutralize other toxin as rapidly as it is 

 developed. 



Infection occurs almost invariably directly through 'an 

 injury in the skin. Nail punctures in a horse are particu- 

 larly apt to result in tetanus as they introduce the organism 

 deep into the tissues and after the superficial healing with 

 the exclusion of air which takes place, conditions become 

 right for rapid multiplication. The statement that a rusty 

 nail is particularly apt to produce tetanus is in the main 

 true, inasmuch as it has much more opportunity to come in 

 contact with dirt; furthermore, particles of rust will gain 

 entrance to the wound and will not be brushed off by the 

 skin as the nail enters. 



Occasionally, particularly in the horse, there are in- 

 stances of so-called cryptic infection in which it is not pos- 

 sible to demonstrate the wound through which the organism 

 producing the disease has entered. It is possible that the 

 organisms may circulate occasionally in the blood stream 

 and be able to localize and grow only when the tissues have 

 been injured in some fashion. This would explain, for ex- 

 ample, the development of tetanus following a bruise or a 

 fractured bone when the skin has not been broken. 



CLOSTRIDIUM CHAUV^I 



Synonyms. Bacillus chauvcei, Bacillus feseri, Bacillus 

 anthracis symptomatici. 



This organism is the specific cause of the disease black- 

 leg, symptomatic anthrax, quarter evil or quarter ill in 

 cattle. 



Morphology. The Clostridium chauvcei is a relatively 

 large organism, rod-shaped with rounded ends, rarely in 

 pairs, usually single, 0.5 to 0.6 X 3-5/x. The organism, 

 even in tissues, practically never occurs in chains. This is 

 of some value in differentiation from the rather closely 

 related Clostridium o&dematis. The organism is motile by 



