H5 



a putrid mass,* and the palm eventually dies, as it has no power 

 of branching or of producing a new growing point. 



14. Trees which only present external signs of disease to the 

 experienced observer show that apparently the roots are probably 

 the parts which become first affected. After a considerable 

 number of these have been rendered useless in contributing to the 

 life of the plant, changes take place which result in a sour-smell- 

 ing red discoloration in the stem that probably commences at the 

 level of the ground and extends upwards. 



The position of this red discoloration would appear to vary in 

 the stem directly with the roots that are affected, and it has been 

 repeatedly noticed that when a ' middle' ring of leaves shows 

 signs of yellowing, the discoloration is found towards the centre, 

 while if the lowest leaves become wilted, the stem presents a ring 

 of discoloration towards the outside of the stem. The petioles 

 also show that they are infested with the mycellium of a fungus 

 for when the leaves become dry and hang down the fructifications 

 push through the epidermis and form pustules of varying size and 

 shape. Eventually, when the vitality of the tree has been reduced, 

 the terminal bud as already noticed becomes infested with a ' rot' 

 which causes the whole cabbage to fall over, resulting in the 

 death of the tree. 



15. Specimens of leaves, roots, stems, petioles, &c. were taken 

 from a considerable number of diseased trees for examination and 

 for cultural and infection experiments. Although it has been 

 impossible to establish with certainty the whole of the life history 

 of the fungus in the short time that has been given to the study 

 of this disease, yet some interesting points have been established. 



ROOTS. — Section of a healthy root shows that on the outside, 

 there is a kind of skin to the root, formed of thick-walled cells, 

 and within this outer layer may be noticed two regions very 

 definitely marked off from each other — the inner is the central 

 cylinder and the outer the cortex. The cells of the central cylinder 

 are of different kinds. The larger of these are thick-walled and 

 are arranged in bundles. They form tubes throughout the length 

 of the roots and are continuous with similar ' vessels' in the stem 

 and leaves. It will be noticed that this portion of the root 

 is hard, for the walls of the cells are lignified and serve 

 for the maintenance of the shape of the root, and also 

 for the transference of water and food in solution from 

 the root to the stem and leaves. Around these vessels are 

 packed numerous thin-walled cells and fibres. The cortex is 

 composed of thin-walled cells loosely arranged. They are uniform 

 in shape and contain a lining of protoplasm — living matter — and 

 also a large quantity of water. It is the contents of these cells 

 that keep them rigid and make them pack closely together. 



Microscopic examination of diseased roots was made in longi- 



* When a coco-nut palm is affected by any disease or pest, the terminal bud, in 

 the advanced stages, becomes involved in a rot. This must not be confused with 

 ' bud-rot' which appears to be a specific disease, as the roots, stem and leaves are 

 sound, while the bud is in a diseased condition. 



