156 HISTORY AND CAUSE OF THE COCONUT BUD-EOT. 



is lost sight of. It is at this stage that the insect grubs referred to make their appear- 

 ance, possibly attracted by the smell. * * * 



It is only in the early stages, before the wet rot starts, that the true cause can be 

 made out. This is a fungus of the genus Pythium, a near ally of the Phytophthora 

 found in koleroga. 



In no other palm than the coconut has there been shown to be a rot 

 of the crown due to bacteria. In the royal palm, in the areca or 

 betel-nut palm, and in the palmyra palm there occurs, however, 

 a soft-rotted condition, and in all cases bacteria are present. In the 

 areca and in the palmyra palm the disease is said to be due to fungi. 

 It would be of great value to ascertain if bacteria would not bring 

 about a similar condition. Palm trees are difficult subjects for 

 experimentation, and yet it would seem as though the fleshy part of 

 the crown, i. e., the growing point, furnishes unusually good oppor- 

 tunities for the work of bacteria, especially soft-rot bacteria. 



In a recent publication ^ Mr. Butler describes in full the bud-rot 

 of the palmyra and coconut palms as he has found it in India. He 

 made several apparently successful inoculations with Pythium 

 palmivorum, one of which was on the coconut palm and the others 

 on the palmyra. It must be noted that the inoculations were not 

 made with pure cultures, at least not pure from a bacteriological 

 point of view. This would seem to lay the results open to question. 



MICROSCOPIC STUDIES. 



The effect of the bacteria on the tissues can readily be seen by 

 studying infected material under the microscope. Microtome 

 sections stained with carbol fuchsin are best adapted for this purpose. 



From the section it is evident that the bacteria may gain entrance 

 through stomata (PI. XIII, fig. 1) and from the inoculation experi- 

 ments described on other pages it is known that they also effect an 

 entrance through wounds. The germs multiply at the pomt of 

 entrance and cause a shrinking of the cells immediately surrounding. 

 They rapidly pass into the interstices and between the walls of 

 normal colls (PL XIII, fig. 2), far in advance of the collapsed tissues. 



The cells of the fundamental tissues have bordered pits in their 

 walls, or it is possible that they are actually pores. The scleren- 

 chyraa cells have greatly thickened walls and in consequence have 

 much deeper pits, which appear in jilaces to be actual canals. These 

 canals pass to the middle lamellae, but it is not certain that they 

 pass through them. In some of the vessels the pits are so numerous 

 as to give the form of papillae to the thickened wall. Comparison of 

 the pits of the vessels with those of the fundamental tissues is not to 

 be taken to indicate that they are analogous, but merely to show 



1 Butler, E. J. The Biul-Rot of Palms in India. Memoirs of the Department of Agriculture in India, 

 vol. 3, no. 5, 1910, pp. 221-280. 

 228 



