318 BACTERIA. 



the saliva from a child in whom the disease was developing 

 as the result of the bite of a mad dog. He took a little of 

 the saliva from this child and introduced it into a small 

 pocket under the skin of a healthy rabbit ; he found the 

 animal dead at the end of a couple of days. Taking some 

 of the saliva of this animal, he treated another rabbit 

 in a similar manner with a like result, but he also dis- 

 covered that the blood of the first rabbit when introduced 

 under the skin of another rabbit also produced the disease 

 in a most virulent form, so virulent indeed that the old 

 question of septic versus other specific infective organisms 

 again cropped up, and it was suggested that the animals 

 had died of septic poisoning due to the presence of ordinary 

 septic organisms in the saliva, and therefore in the blood 

 of the animal that had first been inoculated with the 

 saliva. The fact, also, that the symptoms of hydrophobia in 

 many cases resemble so markedly those of another form of 

 blood poisoning tetanus or lockjaw and the extremely 

 rapid course that it ran in the animals inoculated, made it 

 a matter of extreme difficulty to determine the exact nature 

 of the symptoms, and rendered it impossible for Pasteur to 

 say whether he was dealing with hydrophobia or with some 

 other form of specific infective poisoning. He found, how- 

 ever, that it was specially in the later stages of the disease 

 that hydrophobic symptoms became tetanic in character. 

 After the bite there may be no symptoms at all for a month 

 or six weeks, or even in some cases for twelve months, during 

 which time the poison lies latent in the system, or though 

 active, gives rise to no symptoms. This period is known, 

 technically, as the period of incubation. At the end of this 

 incubation period the wound first of all becomes slightly 

 uncomfortable ; there is itching, and the heat becomes almost 

 intolerable, especially as this is usually accompanied by a 

 sharp stinging pain ; the patient becomes feverish and very 

 thirsty ; the face is pallid and has a peculiar anxious expres- 

 sion, the muscles of the face being drawn and restless, and 

 gradually this expression amounts to one of actual terror or 

 horror. On the second or third day the patient becomes 

 much more excited, is restless in every sense of the word, 

 and a very peculiar feature is that he has a characteristic 

 habit of giving a suspicious side glance as though con- 

 stantly looking out for some hidden danger ; then as the 



