FIELD STUDIES OF THE DISEASE. 51 



It seems most likely, in the face of all this, that insects are the 

 carriers. In view of the fact that they are found so commonly on 

 diseased tissue it seems very possible that they might carry off some 

 • organism either attached externally to their bodies or legs, or taken 

 internally in the cpurse of feeding and subsequently excreted upon 

 healthy tissues. With the exception of fly larvas, earwigs are the 

 most common insects. Some of these were collected from diseased 

 tissues, carefully washed for 20 seconds in mercuric chlorid (1:500), 

 then rinsed in water and placed in tubes containing Dolt's medium 

 (p. 79). The insects were well crushed in the tubes so that any 

 bacteria from the digestive tract would come in contact wdth the 

 medium. 



Transfers were made in Washington from these tubes (eight in 

 number) to beef bouillon, and an attempt was made to isolate the 

 coconut organism. Plates poured from four out of the eight tubes 

 showed among many a few colonies resembling the coconut organ- 

 ism. Transfers from each of the four plates to litmus milk gave the 

 typical reaction. Transfers from the litmus milk to nitrate bouillon, 

 to fermentation tubes with neutral red, to gelatin, and to Dunham's 

 solution, likewise gave the reaction of the coconut organism. Thus, 

 this investigation of the insects, while much too incomplete for 

 proof, indicates that the disease-producing organism may be found 

 in the intestines of earwigs; and such being the case, these insects 

 may be at least partly responsible for the distribution of the disease.^ 



It seems possible also that turkey buzzards may be responsible 

 for carrying the disease germ from tree to tree. These birds are 

 found in all the tropical localities where the bud-rot occurs, and 

 they may commonly be seen in diseased trees. That they feed on 

 the infected tissues is uncertain, but it seems probable that they 

 do. Such tissues have a very bad odor — at times it reminds the 

 writer strongly of an abattoir — and it is likely that they are attracted 

 by it.2 It does not seem improbable that such birds may feed on 

 the material or at least get some of the organisms on their feet, after 

 which it is an easy matter to spread the infection. In the hope of 

 ascertaining the probability of the coconut organism occurring in 

 the digestive tract of these buzzards some of the fresh dropping was 

 placed in tubes of Dolt's medium. Several plates were made, t^^'ice 

 for each of the several bouillon tubes. In every case a small pro- 

 portion of the resulting colonies appeared to be the coconut organ- 



1 In one of the last trees cut down at Yumuri, Dr. Smith found two larvae in the rotting bud not far from 

 the sound tissues. These larvae were of a gray color and probably similar ones had been overlooked. They 

 were put into a clean petri dish and brought to Washington. On the way they pupated and later one of 

 them passed into the imago state and was identified by Mr. Coquillett as Hermetia illudens L., a common 

 scavenger fly of the Tropics. 



2 Dr. Smith states that twice, at Baracoa, buzzards swooped down on the rotted hearts of palms he had 

 laid aside for study and would have carried the material off if he had not made a frantic rush to protect it. 



228 



