BACILLUS COLT, THE CAUSE OF BUD-ROT. 141 



admission that possibly mixed cultures were used. This alternative 

 is one that no bacteriologist would like to admit, and yet to be perfectly 

 honest it must be considered. 



It will be noted that all of the isolations of organisms for inocula- 

 tion in the case of these successful infections (those Avith organisms 

 apparently not Bacillus coli) were made in Cuba at a relatively high 

 temperature and without the best facilities for work. Bacterial 

 colonies grew luxurianth^ in 18 hours, and when the plates had some 

 of the widespreading colonies, they became entu-ely overgrown in 

 24 hours, even when sown in the thinnest possible manner. One- 

 half or more of a plate would contain these radiate and rapidly 

 spreading colonies. In the case of the plates which in 24 hours 

 showed a})parently only round colonies, after 48 hours some of them 

 showed a tendency to branch. While it does not seem probable 

 to the writer, yet it would seem necessary to admit the possibility 

 in these particular cases of making a transfer from a colony which 

 was apparently a- single one, but which in reality consisted of more 

 than one species of organism. The different forms of colonies 

 produced by different organisms and the secretions produced by 

 some species inimical to the growth of others appear to reduce tliis 

 possibility to a minimum. However, in the case of numerous 

 rapidly growing organisms, all of which are white, wet-shining 

 growths on agar, and varying in their form of colonies, this possibility 

 can not be entirely ignored. The facts of the case, though, do not 

 seem at all to warrant the supposition that the successful infectious 

 with organisms apparently different from Bacillus coli weaken the 

 claim that Bacillus coli itself causes the bud-rot. 



It has been shown in foregoing pages that certain organisms were 

 isolated from bud-rot tissues, were inoculated mto healthy trees, and 

 carried through a series of isolations and reinoculations, and that 

 certain of the organisms used in these experiments were identical with 

 each other and with Bacillus coli. In the very first isolations Bacillus 

 coli was unthought of, those colonies being taken wliich were in the 

 majority and wliich were thought to be the cause of the disease. Only 

 subsequent work revealed to the writer that the organism was 

 Bacillus coli, or at least indistinguishable from it. Later, with 

 inoculations of Bacillus coli isolated from animals, a disease similar 

 to bud-rot was produced. 



Finally it was decided to search directly in the diseased tissues 

 for Bacillus coli. Material was secured on two different occasions. 

 On August 16, 1910, material from two trees was obtained in Baracoa, 

 and transfers of the infected material were made under clean condi- 

 tions to tubes of Dolt's synthetic medium. Then, in Washington, 

 platings were made and the routine examination for Bacillus coli 



228 



