414 BACTERIA IN INFECTIOUS DISEASES. 



" Microscopical examination of the blood of pigeons 

 attacked with variola shows that this liquid contains an 

 infinite number of living microbes. This alteration 

 is constant, and is true in the case of pigeons attacked 

 spontaneously, as well as of those which have been sub- 

 jected to experimental inoculation. 



u Upon studying the development of the microbes in 

 the blood, the following facts worthy of note may be 

 observed. The first important point consists in the 

 progressive development of the organisms in correspond- 

 ence with the progress of the disease. Their appear- 

 ance in the blood always precedes the appearance of 

 morbid phenomena. This fact is especially easy of 

 verification in pigeons which have been inoculated, 

 by means of a vaccination needle, either with the blood 

 of a sick animal, or with the liquid contained in the 

 pustules. 



u If after inoculation we examine each day the blood 

 of pigeons, we shall find that during the first, second, 

 and often the third day, it presents nothing abnormal in 

 its appearance ; however, towards the end of the third 

 day an attentive examination will already demonstrate 

 the presence of the microbes in the blood ; the following 

 days the parasite increases rapidly, and when the pigeon 

 presents manifest symptoms of illness, a microscopic 

 preparation of the blood offers myriads of microbes in 

 movement. 



u This period, from the time of inoculation until the 

 development of morbid phenomena, corresponds with 

 the period of incubation so characteristic of other viru- 

 lent and contagious maladies. The greatest number of 

 parasitic organisms are found in the blood just before 

 the eruption appears. Subsequently they gradually 

 decrease in number. 



u The pus of the pustules contains the characteristic 



