80 



HISTORY AND CAUSE OF THE COCONUT BUD-EOT. 



part wet sliining, smooth, and with raised margins. Near the top the 

 growth consisted of more or less isolated colonies. In tube No. 1 a 

 subsequent tendency to bleaching of the litmus appeared. In all the 

 tubes the litmus was first reddened. 

 This medium is made up as follows : ^ 



Cubic 

 centimeters. 



Purified agar (3 per cent solution) 500 



Glycerin 5 gramsl 



Ammonium phosphate. .1 grami 500 



Distilled water J 



NaOH was used to neutralize, and 1 per cent lactose added just 

 before sterilization. Litmus was added in sufficient quantity to make 

 a good blue color. 



NEUTRAL RED USED IN VARIOUS MEDIA. 



The use of neutral red in differentiating Bacillus coli from other 

 species has been widely recommended. A few other organisms be- 

 have in a similar way, but the reaction at least differentiates a group 

 of organisms if not a single one. A useful way to use neutral red in 

 determining Bacillus coli is in fermentation tubes. This method and 

 others are here described. 



Table XII. — Growth of coconut and Bacillus coli cultures of March 15, 1910, in fer- 

 mentation tubes, using neutral red with 1 per cent dextrose and 1 per cent peptone solu- 

 tion in river vjater, incubated at 37° C. 



The greenish-yellow color seen in tubes 5 and Bacillus coli a of this 

 experiment is typical of the noutral-red reaction. Tubes 5 and 5 a, 

 Bacillus coli and Bacillus coli a, derived, respectively, from 5 and 

 Bacillus coli, did not show the same reaction. As the two tubes each 

 from different cultures were made under the same conditions from the 

 same tubes, this difference in results suggests an unreliability in the 

 reaction. Further work, however, tends to show that the greenish- 

 yellow or canary -yellow color is generally present. In other media 

 it is demonstrated more clearly. 



■ 1 Dolt, Maurice L. Simple Synthetic Media for the Growth of Bacillus Coli and for Its Isolation from 

 Water. Journal of Infectious Diseases, vol. 5, 1908, p. 625. 



228 



