396 



might be found better to add creosote in the latex, and simply cure 

 the biscuits in that form. .Mr. Parkinson who worked out the 

 methods of making biscuits in 1898 used creosote and if they refer- 

 red to a circular issued in that year they would find that he had 

 calculated the amount of acetic acid and creosote to be used. They 

 kept the biscuits and except some surface mould — they had kept 

 their light colour for years together. He thought on the whole to 

 add a little creosote to the milk and then coagulate it would perhaps 

 make the rubber better to handle. " 



The experiment of creosoting latex was one of the earliest 

 attempted here. The fresh latex was mixed with a little creosote 

 and dried naturally in block, without the use of acetic acid. The 

 idea was that the darkening of the colour of the rubber was due to 

 bacterial or fungal action and the creosote would disinfect it and 

 keep it light colored. With a very little creosote it was found that 

 the rubber did remain a little lighter in colour. With more creosote 

 - it was not much improved and it went tacky and was spoiled. It 

 seemed to have no useful action on the rubber, and except in very 

 small quantities was injurious ; whereupon this experiment was 

 abandoned. 



H. N. R. 



DISEASES OF HEVEA BRASILIENSIS. 



Leaf Diseases — The leaves of seedling Hevea brasiliemis , are 

 extremely liable to injury by mechanical means or by fungi. These 

 injuries are usually local, ie., they affect a small part of the leaf 

 only and do not interfere with the functions of the remaining tissue. 

 The appearance of a diseased leaf depends to a great extent upon 

 the structure of the leaf itself, and in the present case practically all 

 injuries cause a whitish semi-transparent area bordered by a brown 

 line. Leaves of older plants appear to be immune to most of the 

 fungi which attack seedlings. The commonest leaf fungus is that of 

 Gray Blight, Pestalozzia Guepini, Desm., this is comparatively 

 harmless on leaves, but kills the seedlings when it attacks the stem 

 at the collar ; the diseased patch usually takes the form of a white 

 ring surrounding the stem, bordered by a narrow red brown line. 

 Equally abundant, but of still less importance, are the leaf spots 

 caused by Helminthosporium hevex, n. sp.; these are small, circular, 

 semi-transparent, and bordered by a purple-brown line. In one 

 instance in which the first leaves of seedlings turned yellow and 

 dropped off, two fungi, which have been named Gloeosporium brmi- 

 neum and Colletotrichum heveaz, were found on the leaves. Phyl- 

 losticta heveae, Zimm., and Gloeosporium elasticao, Cke. & Mass., 

 have also been observed. 



Root Diseases. — The first specimens of root disease were for- 

 warded to Peradeniya as examples of the damage caused by white 

 ants. In old trees the fungus attacks the tap root; this is sub- 

 sequently eaten by termites. The tree, however, continues to 

 obtain a sufficient supply of water from the side roots until it is 



