844 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



PRELIMINARY REPORT ON THE NATURE OF THE BANANA 

 DISEASE PREVALENT AT ALEXANDRIA. 



By De. Looss and G. P. Foaden. 



Some time since a short report on the external symptoms and probable 

 cause of the Banana disease prevalent near Alexandria was communi- 

 cated to the Scientific Committee on December 17, 1901, by Dr. Preyer 

 {see p. ccxxii). 



In December the writers, at the request of the Alexandria Municipality, 

 visited an infected plantation at Gabarri, where the disease was evidently 

 causing great havoc. In addition to this examination on the spot, portions 

 of leaves, stems, roots, &c., were taken for microscopic examination. 



The description given by Dr. Preyer in the article previously referred 

 to correctly describes the external symptoms of the disease, and micro- 

 scopic examinations also indicate that his conclusions were correct as 

 far as they went. It is clear that parasitic worms, if they are not abso- 

 lutely and entirely the cause of the disease, at least play by far the most 

 important role in bringing it about. They live chiefly in the roots, for 

 on examining the rootlets some little distance from the parent plant it 

 was found that a considerable number of them had died off and were in a 

 state of putrefaction, while others which were still living showed the 

 knobby appearance mentioned by Dr. Preyer ; others again were apparently 

 healthy. On removing the finer particles of earth adhering to the latter 

 their surfaces were seen to be covered with numerous dark dots. These 

 proved to be the places where the youngest terminal offshoots of the roots 

 branch off from the main rootlets. Some of them were still found in 

 connection with the latter, but almost all were in different stages of de- 

 composition, this evidently starting from the base of the offshoots and 

 eventually leading to their death and disappearance. 



The conclusions which follow have been derived from an examination 

 of these three different aspects of the roots, but the whole trunk of a very 

 diseased plant was also examined together with the entire root system. 

 These main branches of the root did not show, in this case, the knobbed 

 appearance referred to ; a few showed the dotted appearance, but the 

 majority were dead. The number of worms present was considerably 

 fewer than in the secondary roots. As far as an opinion can be expressed 

 on evidence before us, it appears that the secondary roots are particularly 

 singled out for attack, and, becoming finally destroyed, the food supply of 

 the plant is partially cut off, the circulation of the sap is retarded, growth 

 checked, and the external symptoms observed and described by Dr. Preyer 

 are the natural consequence. Where putrefaction is going on other 

 minute forms of life are found, and, owing to the favourable conditions 

 present, multiply at an enormous rate. There were found in the plants 

 examined several species in great numbers of Rotatoria and Infusoria j 

 but all these animals, in spite of their numbers, have nothing to do with 



