FIELD STUDTES OF THE DISEASE. 39 



bacteria frequently do, and from the observations of Dr. Smith it has 

 been seen that only bacteria are in the advancing margin of the 

 decaying tissues. Moreover, it has since been claimed that Uredo 

 coccivoro is nothing else than the normal scales of the coconut leaf.^ 



Dr. Davalos, of the bacteriological laboratory of Havana, isolated 

 in 1886 what he claimed to be Bacillus amylohader, which he believed 

 was the cause of the soft rot.- 



Dr. Plaxton, of Jamaica, in 1891, before the Institute of Jamaica,^ 

 showed under the microscope some slides of a micrococcus which he 

 thought was probably the cause of the coconut disease. In other 

 parts of this paper the writer has quoted many investigators ascribing 

 the cause of the disease either to bacteria or to fungi. The opinions 

 as to the cause of the disease are so various, and hence, reasons for 

 methods of treatment so unsatisfactory, that it has seemed eminently 

 desirable to carry out a clear series of experiments to settle, first, the 

 infectiousness of the disease; second, if infectious, whether due to 

 fungi or to bacteria; and third, if possible, to isolate the organism 

 causing the disease. 



BACTERIAL INOCULATIONS. 



Owing to the height of the trunk and the great size of the crown, 

 inoculation of coconut trees is difficult. The rot is pecuHarly one of 

 soft tissues, so that in order to be effective the bacteria must be 

 placed in the interior among these soft tissues. From the bottom of 

 the crown to the growing point there is commonly a distance of 1 to 

 1.5 meters (fig. 9, from x to y), so that the exact location of a spot 

 suitable for inoculation is hard to determine. Inoculations made 

 below the heart into the trunk fail to produce the rot, since these 

 tissues naturally soon harden as a part of the mature tree. If, on the 

 other hand, the inoculation be made above the heart amid the grow- 

 ing leaves, their extremely rapid elongation takes the inoculation 

 point out from the surrounding soft tissues. The inoculated tissues 

 then become green and membranous and thus resist the advance of 

 the rot. The point of easy inoculation is less than 0.5 meter above or 

 below the growing point, and rather near the center of the tree. 

 (See fig. 8. Inoculation on line BB is desirable; moculation on line 

 AA would seldom be successful.) This often requires an inoculatmg 



I Tamayo, Dr. La Epifltia de los Cocoteros. Revista de Agricultura (Cuba), vol. 9, 1889, pp. 557-8, 



570-1, 584-5. ^ ^ ^ „. . 



Torre, Carlos de la. La Enfermadad de los Cocoteros. Revista de la Facultad de Letras y Ciencias, 

 Universidad de la Habana, vol. 2, no. 3, May, 1906, p. 274. 



"- Davalos, Dr. Kevista de Agricultura. Boletin Oflcial del Clrculo de Hacendados de la Isla de Cuba, 



vol. 9, no. 29, 1889. 

 3 Plaxton, Dr. Journal of the Institute of Jamaica, vol. 1, 1891-1893, pp. 43-41. 



■22S 



