118 HISTORY AND CAUSE OF THE COCONUT BUD-EOT. 



No change appeared in any of the cyhnders but No. 1, and that was 

 one of the Bacillus coli tubes which blackened the cyhnder without 

 showing any growth on the surface. It is evident in any case that 

 such woody tissues of the coconut tree furnish a poor medium for 

 the growth of the organism. 



TEST 2 OF D. RIVAS.' 



One c. c. of a 10 per cent solution of NaOH and 1 c. c. of a 50 per 

 cent solution of H2SO4 are added to 5-hour cultures incubated at 37° 

 C. in neutral sagar-free bouillon. A purple color resulting from the 

 addition of the NaOH and H2SO4 is the test. The color is said to 

 appear upon the addition of acid and to be discharged upon the 

 addition of an alkah in excess, and is not produced in the presence 

 of sugar. The reaction is thought to be closely allied to indol pro- 

 duction and is dependent upon the action of the bacteria upon 

 some proteid substance. Experiments were conducted as follows: 



1. Neutral bouillon cultures grown at 37° C. Tubes inoculated at 10 a. m. on 

 March 17 and tested at 4.30 p. m. of the same day. No purple coloration appeared 

 either then or after allowing the tubes to stand 16 hours. 



2. Sugar-free neutral bouillon tubes were inoculated at 11 a. m. on April 12 and 

 tested at 4 p. m. The tubes were moderately clouded, but no purple color appeared 

 on the addition of the reagents. This bouillon was made eugar-free by growing 

 Bacillus coli in it and then filtering, titrating, retubing, and sterilizing. The tubes 

 after sterilization titrated zero on Fuller's scale. 



3. Sugar-free bouillon as before. Tested after three days, but no purple reaction 

 appeared, although the tubes containing the reagents were allowed to stand 48 hours. 



The failure of the cultures, both Bacillus coli and those of the 

 coconut, to respond to this test is not clear. Possibly bouillon only 

 normally free from muscle sugfjr should have been used. 



PEPTONE WITH LEVULOSE, GALACTOSE, AND MANNIT IN FERMENTATION TUBES. 



Table XXVIII shows that all the coconut cultures grow well in 

 levulose, galactose, and mannit, and at the same rate as Bacillus 

 coli. The gas production in levulose averaged in 15 days 15 mm.; in 

 galactose 35 mm. ; and in mannit 25 mm. 



I Rivas, D. Contribution to the Differentiation of Bacillus Coli Communis from Allied Species in 

 Drinking Water. Journal of Medical Research, vol. 18, 1908, pp. 81-91. 



228 



