190 LOUIS PASTEUR. 



microbe-ferment of the butyric fermentation was the 

 very agent of decomposition, he prepared an artificial 

 liquid formed of phosphates of potash, of magnesia, 

 and of sulphate of ammonia, added to the solution of 

 the fermentable matter, and in this medium he caused 

 the microbe-ferments to be sown in a pure state. 

 The microbe multiplied, and provoked fermentation. 

 From this liquid he could pass to a second or third 

 fermentable liquid composed in the same manner, . 

 and so on in succession. The butyric fermentation 

 appeared successively in each. Since the year 1857 

 this method was supreme. In this particular research 

 on the disease of splenic fever Pasteur proposed 

 to isolate the microbe of the infected blood, to cul- 

 tivate it in a state of purity in artificial liquids, and 

 then to come back to the examination of its action 

 on animals. But as, since his attack of paralysis 

 in 1868, Pasteur had not recovered the use of his 

 left hand, and consequently found it impossible to 

 carry on a long series of experiments alone, he was 

 obliged to seek for a courageous and devoted assistant. 

 He found one in a former pupil of his at the Ecole 

 Normale, M. Joubert, now Professor of Physics at the 

 College Rollin. If M. Joubert incurred the danger of 

 these experiments on splenic fever, he also shared 

 with Pasteur, in the Comptes-rendus of the Academy of 

 Sciences, the honour of the researches and the triumph 

 of the discoveries. 



