12 THE CONTAGIOUS TYPHUS 



We selected six healthy sheep, which we 

 kept well supplied with provisions ; we covered 

 these healthy sheep with parasites (acari). 

 On every one of these sound, well-fed sheep, 

 the microscopic animalcube died off without 

 generating the cutaneous disease ; for the 

 blood, the humours, and the skin of sound 

 and healthy sheep constitute a soil unfavour- 

 able to the propagation of these parasites, and 

 actually starve them to death. 



After this first experiment, we subjected 

 these six sheep to a deficient diet ; they grew 

 lean, their blood was impoverished, and then 

 all we had to do was to lay upon them not 

 thousands and thousands of these parasites 

 as we had done in the first instance but one 

 solitary female in a state of fecundity ; and the 

 parasitical distemper unfolded itself so fiercely 

 as to cause the death of three of these sheep 

 on which the test was allowed to run its 

 course ; whilst the other three sheep, having 

 been restored in time to a recoverable con- 

 dition just as they were about to drop off, 

 were thoroughly cured, without any special 

 treatment, by the sole influence of good food 

 and ordinary hygienic attention. 



