ACID FUCHSINE. 277 



from whence the colour was diffused to the upper stratum, gradu- 

 ally fading as it approached the periphery. The deeper strata 

 were unchanged, the line of demarcation between the upper 

 upper and the lower portions being sharply drawn. This condition 

 was changed little by little, the lower portions gradually assuming 

 a red colouration. Twelve days later the cultures of the Bacillus 

 typhosus were red in their whole extent. This shows quite con- 

 clusively that the changes are due to an oxygenation of the media 

 by the action of the culture. Shake cultures of the same bacteria 

 were made with the same results in a much shorter time, the 

 cultures of the Bacillus coli commimis producing the characteristic 

 bubbles on the third day. The red colouration of the cultures of 

 the Bacillus typhosus began in this case by a narrow, superficial 

 zone that gradually extended to the whole tube. 



Shake cultures in Dunham's solution, with glycerin and acid 

 fuchsine and gelatin, showed the difference between the Bacillus 

 coli commwiis and the Bacillus typhosus in twenty-two hours after 

 they had been planted, in spite of the fact that on account 

 of extremely hot weather the cultures were kept at 50° F. As in 

 the cases before mentioned, the Bacillus coli commimis produced 

 an acid change, making more intense the pink colour of the 

 cultures, while the Bacillus typhosus did not produce any acid 

 until the third day. It is thus seen that in this gelatin medium 

 the Bacillus typhosus produces acid in a shorter time than in the 

 agar or liquid media. 



The Bacillus typhosus and the Bacillus coli comjuutiis were also 

 planted in the somatose solution, with glycerin and acid fuchsine. 

 The results were the same as those observed with Dunham's 

 solution with glycerin, but the changes were brought about in less 

 than twenty-four hours- At the end of this time cultures of the 

 Bacillus coli communis exhibited a bright red colour. 



It will be seen that, by growing the intestinal organisms in the 

 medium mentioned above, we are enabled to distinguish organisms 

 that are so often confounded with each other. Dr. Penny states 

 that he is now experimenting with other intestinal bacteria, more 

 especially the spirilla, and the results so far obtained are promising, 

 and will be published. 





