140 HISTORY AND CAUSE OF THE COCONUT BUD-KOT. 



From the foregoing remarks on the origin of these cultures it will be 

 seen that Koch's rules for proof of an organism causing a disease have 

 been followed out. The many additional inoculations tend only to 

 corroborate these results. 



Thus, having shown, as above stated, that these six cultures are 

 similar to each other and to Bacillus coli, the following conclusion 

 seems inevitable: The organism (No. 6) isolated from a naturally 

 diseased tree in Cuba on August 7, 1909, was Bacillus coli. 



There have been some slight differences as already noted between 

 Bacillus coli and the six coconut organisms. They consist in the 

 variable differences found in the nitrogen-free media, with the am- 

 monium compounds, in strength of reaction on starch media, in 

 constancy of reaction in lactose-peptone solution, and in amount of 

 indol produced. In no case is there any definite or constant differ- 

 ence other than in strength of reaction. Taking the reactions as a 

 whole, Bacillus coli has at times appeared to differ from the coconut 

 organisms to the sHght extent already indicated, differing from them 

 more than they have differed from each other with the exception of 

 No. 1, but not more than the various strains of Bacillus coli differ 

 among themselves. This condition indicates that the organisms 

 isolated from the coconut tree are forms of Bacillus coli, or at least 

 belong in the colon group, and can not be distinguished from Bacillus 

 coli by any of the current methods of bacterial separation. 



Moreover, and tliis appears to the writer to be a decisive point, 

 typical Bacillus coli has been shown to be capable of jiroducing typical 

 bud-rot. The conclusion, therefore, seems inevitable that the 

 organism or organisms of the colon group, commonly called Bacillus 

 coli, must be considered as the cause of the coconut bud-rot. 



In the course of such an extended study on a disease as this has 

 been there naturally occur certain results some of which tend to 

 weaken the case and others to strengthen it. The many successful 

 inoculations and the similarity of the cultures injected and isolated, 

 together with the similarity of many other cultures isolated from 

 diseased coconut material by the writer and earlier by Dr. Smith 

 (p. 142) all tend to strengthen the case. On the other hand, success- 

 ful inoculations by the writer mth cultures of variable appearance 

 rather tend to weaken the argument. These results may be ex- 

 plained by the supposition tliat other organisms than Bacillus coli 

 also produce the bud-rot, or that what passes for Bacillus coli includes 

 a group of closely related but not identical organisms. As there is 

 no conclusive evidence for or against such a proposition, this question 

 must remain open. It may be said, however, that the writer does 

 not consider this a probable case. The only alternative in explain- 

 ing the successful infections with apparently different cultures is the 



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