FIELD VOLES IN THESSALY. 311 



my former paper, the bacillus, when absorbed through the digestive 

 system, proved only fatal to house-mice and field-mice, but 

 appeared to be perfectly innocuous to many other species of 

 animals, such as cats, rabbits, guinea-pigs, pigs, small singing 

 birds, pigeons, and fowls. I also stated that it was important for 

 the practical utility of the bacillus to ascertain by numerous 

 experiments that all farm-animals enjoyed similar immunity. 

 I therefore made experiments in feeding sheep, which Councillor 

 Becker, of Eldena, placed at my disposal in the most obliging 

 manner. The results fully answered my expectations, for though 

 the sheep is particularly susceptible to disease, those on which 

 I experimented took enormous doses of the bacillus without 

 showing the least symptom of illness, whilst all the voles which 

 were treated with the same bacillus died, without exception, of 

 "mouse-t3'phus" after the usual period of from eight to fourteen 

 days. The results of the experiments rendered it in the highest 

 degree probable that the larger farm-animals, such as horses and 

 oxen, would likewise be proof against infection. In any case it 

 seemed to me that the practical application of the bacillus might 

 be tested without hesitation in the Thessalian fields which were 

 threatened with such danger, where almost the only animal of 

 importance in the neighbourhood, the sheep, had been proved to 

 be unsusceptible to it. 



On March 29th, the Greek Government, influenced by the 

 report of his Excellency the Greek Ambassador at Berlin, 

 M. Rangabe, who had studied the pamphlet I sent him, and 

 perhaps partly also by telegraphic information, respecting the 

 bacillus which I had discovered, from the eminent French bac- 

 teriologist, Prof. Pasteur, requested me to supply them with tubes 

 of the virus for experiment in Thessaly. I felt no further hesi- 

 tation about carrying out the experiments on a large scale. 



It was first necessary for me to explain how the experiment 

 was to be conducted, that there might be some certainty of 

 attaining the desired result. I had learned from my experiments 

 and observations that within the narrow limits of a cage the 

 disease was communicated from one infected animal to another in 

 the course of a few weeks, so that at length all were attacked. 

 The infection was communicated by a healthy animal taking the 

 bacillus in food fouled by the fceces of those already ailing which 

 were charged with bacilli ; and afterwards by their devouring the 



