Disease Generated by Infusoria. 179 



in adults and old animals than in young ones. During this 

 period the bacteriums are slow to appear, but from the moment 

 of their occurrence the animal has but a short time to live. 

 The longest interval that I have observed between the appear- 

 ance of the bacteriums and the death of the inoculated animals 

 was five hours, thus the mean length of the incubation period is 

 thirty-five hours. 



" During the incubation period the animal loses nothing in 

 power or agility ; it is only in the last two hours, when the 

 bacteriums exist in notable quantity, that the rabbit ceases to 

 eat or to run. It then lies on its belly, grows rapidly weak, 

 and dies without any special symptom. Sometimes, however, 

 death is preceded by slight convulsive movements/'' 



M. Davaine goes on to say that autopsy shows a healthy 

 condition of the large organs, but the heart and large vessels 

 are distended by very cohesive clots. Coagulation of the blood 

 is thus the only apparent cause of death. During life the 

 microscope shows this coagulative action, as the increase of the 

 bacterium is found to be associated with a viscosity of the red 

 globules, and a tendency for them to adhere together. The 

 large organs only contain the bacteriums as a consequence of 

 their vascularity, and the spleen, which is very vascular, 

 appears the focus of their reproduction. 



M. Davaine concludes this paper by observing that expe- 

 rience shows the appearance of bacteriums in the blood pre- 

 cedes the phenomena of disease, and it is therefore natural to 

 refer the latter to the former, which enjoy an individual vitality, 

 and propagate themselves after the manner of living beings. 

 While the blood only contains them in the germ ; while their de- 

 velopment is not effectuated, the morbid phenomena are not 

 produced. But if the question is examined from another point 

 of view, it seems probable that blood in which they have not 

 made their appearance would be incapable of propagating 

 them in a new animal, that is to say, that during the period of 

 incubation they could not be sown, and the spleen disease (sang 

 de rate) could not be communicated by inoculation. 



In a third paper M. Davaine states that he inoculated a 

 healthy and vigorous rabbit with three or four drops of blood 

 from another rabbit infested with bacteriums, but still living. 

 Forty-six hours after the inoculation, being six hours beyond 

 the mean time of death, he examined the inoculated rabbit 

 without finding any bacteriums. He then took from its ear 

 twelve to fifteen drops of blood, that were injected into the sub- 

 cutaneous tissue of a third rabbit, about two-and-a-half months 

 old. Nine hours after this the rabbit first inoculated was found 

 to contain a quantity of bacteriums, and some blood from its 

 ear was introduced into the sub-cutaneous tissue of a fourth 



