254 BACTERIA 



less, has a high-toned bark, and snaps at various objects. 

 Sometimes it exhibits depraved appetite; spasms of the 

 throat follow, and these soon develop into convulsions, 

 which are followed by coma and death. In man the incub- 

 ation period is fortunately a very long one, averaging about 

 forty days. Nervous irritability is the first sign; spasms 

 occur in the respiratory and masticatory muscles, and the 

 termination is similar to rabies in the dog. The symptom 

 of fear of water is a herald of coming fatality. 



Although a number of the workers at the Pasteur Institute 

 and elsewhere have addressed themselves to the detection 

 of a specific microbe, none has as yet been found, although, 

 in the opinion of Pasteur, such an agent may be suspected 

 as the cause. 



Pathologically rabies and tetanus (see page 168) are closely 

 allied diseases, and the recent remarkable additions to our 

 knowledge of the latter disease only make the similarity 

 more evident. There are in rabies three chief sets of post- 

 mortem signs. First, and by far the most important, are the 

 changes in the nervous system. Here we find patches of 

 congestion in the brain, and breaking down of the axis 

 cylinders of the nerves. The stomach, in the second place, 

 exhibits haemorrhagic changes, not unlike acute arsencial 

 poisoning. Thirdly, the salivary glands show a degenerat- 

 ive change in a breaking down of their secreting cells. 

 Roux has pointed out that in life the saliva of a mad dog 

 becomes virulent three days before the appearance of the 

 symptoms of disease. 



We may now turn to the method of treatment which was 

 introduced by Pasteur. Before his time cauterisation of the 

 wound was the only means adopted. If more than half an 

 hour has elapsed since the bite, cauterisation is of little or 

 no avail. The basis for Pasteur's treatment was the differ- 

 ence in virulence obtainable in spinal cords infected with 

 rabies. Pasteur found that drying the cord led to a lessen- 



