672 RUBBER 



orange, or red spots. The use of sodium bisulphite in 

 the preparation of rubber, which by chemical action is 

 partly converted into the hygroscopic magnesium salt in 

 the latex, and the preparation of blanket or thick crepe, 

 which dries slowly, almost invariably result in the 

 development of these spots, and were probably the cause 

 of the somewhat widespread epidemic during 1911 in 

 the Federated Malay States. Spot diseases, as would be 

 expected, are very prevalent in unsmoked sheet and in 

 rough crepe on the thick ridges made by the diamond 

 or spirally cut rollers of the crepeing machines, which 

 do not dry as quickly as the thinner portions, hence the 

 advantage of " finishing " crepe on smooth, even-speed 

 rollers. Under ordinary circumstances, if no develop- 

 ment of the " spots " occurs during 1 the first day or two 

 after the rubber is hung in the drying room, the rubber 

 is safe from further attack. The spores, however, may 

 still be present and, as these may be very resistant to 

 desiccation, further development can take place if the 

 rubber is allowed to become moist again. Three very 

 interesting cases in which such subsequent development 

 has occurred have come to the author's notice. In the 

 first two instances samples of rubber which had been 

 sent to Europe from estates were returned to the 

 managers and sent subsequently to the Agricultural 

 Department for report in connection with orange spots 

 on the specimens; the managers of the estates in ques- 

 tion stated definitely that the rubber, when packed and 

 shipped, was perfectly dry and showed no trace of such 

 spots. On microscopical examination the spotted por- 

 tions of the rubber were found to contain numerous 

 spores from which short hyphae had developed, further 

 development appearing to have been arrested. It could 

 only be surmised that the cases of rubber had subse- 

 quently come into contact with water, probably accidental 

 contact with sea water. This idea was amply confirmed 

 in connection with a case recently examined by the 

 author. The rubber in question was received from an 

 estate for dispatch to the London Rubber Exhibition 

 and examined by the Director of Agriculture and myself 

 among other cases before dispatch. The case was 



