LABORATORY AND GREENHOUSE STUDIES. 135 



green hardened tissues (PI. XI) and in plants not making one- 

 quarter as rapid growth as they would have made in the Tropics. 



Experiment No. 5. 



On August 15, 1910, three inoculations were made into coconut 

 trees in Baracoa with a strain of Bacillus coli obtained from Dr. Theo- 

 bald Smith. The three trees were each about C years old and were 

 apparently in a perfectly healthy condition, although they were 

 bordering a grove of some 1,200 trees that had just been entirely 

 destroyed by the bud-rot. 



On September 28 these inoculations were examined. 



Inoculation No. 1 proved to have been made too low. It was 

 below the heart and in the woody tissue. The tissue was entirely 

 rotted about 1 centimeter around the hole from the outside to the 

 interior. On the outer sheaths the brown discoloration extended 

 several centimeters. 



Inoculation No. 2 was the same as No. 1. Here also the inocula- 

 tion was in the wood below the heart. 



Inoculation No. 3 was in the soft tissues above the heart. The 

 hole itself w^as perfectly dry and uninfected in the interior. Extend- 

 ing from the hole upward for 1 meter and only on the inoculated 

 side was the typical soft white rot of the bud-rot disease. The infec- 

 tion was visible on the upper part of the central leaves. There were 

 no insects or other signs of carriers of the disease. It could not be 

 determined if the rot was caused by the inoculation, because, (1) it 

 became more conspicuous from a point 8 centimeters above the hole, 

 but this may have been because of tissues better suited to infection 

 at that point and upward, infectious fluid being injected into all this 

 area; or because (2) by rapid growth the soft injected tissues were 

 carried up beyond the level of that part of the puncture passing 

 through the older tissues. The method of inoculation consisted first 

 in boring a hole to the center of the trunk by means of a 9-millimeter 

 steel bit and then injecting the fluid containing the germs by means of 

 a large syringe. As the terminus of the hole in this case was made 

 into the soft tissues it is very possible that the syringe did not follow 

 the hole throughout, but was pushed to one side in the soft inner tis- 

 sues. Such a condition could not be determined for the reason that 

 the end of the syringe was small and would make only a very small 

 hole, and the tissues were rotted at this point so that any hole, unless 

 very large, would be indistinguishable. The writer considered the rot 

 due to the Bacillus coli introduced by him. On the other hand, it 

 might be claimed that the inoculation failed and that the infection 

 was entirely an outside one. However, if the same kind of organism 

 that was injected could be isolated from the diseased tissues it would 



228 



