BACILLUS TETANI. 341 



ful action ; a larger proportion, more than half of the 

 specimens investigated, caused always, or almost always, 

 tetanus. In the case of mice about as much as lay on 

 the point of a pen-knife, in the case of rabbits four or five 

 times this quantity, was introduced into a small pocket 

 in the skin, made on the back or thigh ; in rabbits the 

 wound was closed by one or two stitches. 



After an incubation period of 1^ to 2J days the Course of the 

 earliest symptoms of the disease appear, consisting in 1 

 slight abduction and stretching of the hinder extremity 

 which is nearest the seat of inoculation, the limb soon 

 becoming completely stiff. In the course of a few 

 hours the hinder extremity on the other side is similarly 

 aifected, and then follow the anterior extremities. Ulti- 

 mately the animals become quite helpless, and generally 

 lie on their backs, while intermittent spontaneous con- 

 tractions of the extensor muscles of the neck and back 

 occur, in which the head is bent backwards, and the 

 posterior part of the body is raised from the surface on 

 which it is resting, the body thus describing a convex 

 line. These attacks can, however, be set up artificially, 

 and may even be caused by knocking the table, or by a 

 slight touch. Breathing is difficult in this stage, the 

 pauses become constantly longer, and finally respiration 

 ceases, and death occurs. In the case of rabbits well 

 developed trismus can be observed. Mice die on an 

 average at the end of 3 days ; rabbits, in whom the in- 

 cubation period usually lasts from 3 to 5 days, die 

 from the 5th to the 7th day after inoculation ; guinea- 

 pigs are also susceptible ; dogs, on the other hand, are 

 completely immune. 



On post-mortem examination of animals which have Post-mortem 

 died with these symptoms, a relatively small amount of a PP earances - 

 pus of a peculiar musty disagreeable odour is found at 

 the seat of inoculation. Besides this, however, no im- 

 portant or constant pathological alteration is noticeable 

 in any organ, in the trunks of the nerves, or in the 

 spinal cord. Microscopical examination of the blood 

 and internal organs was also almost entirely without 

 result ; but in the pus at the seat of inoculation fine 



