170 SPICES 



CHAP. IV 



their ends a number of short arms, usually from 3 to 9 

 in number, all nearly equal in length. At the end of 

 each arm, which is abruptly decurved, is a yellow 

 rounded body, the zoosporangium. These zoosporanges 

 open by a minute hole at the top and let out a number 

 of zoospores, which swim in drops of water by the aid 

 of two minute hairs or cilia, and are thus carried 

 from leaf to leaf by the rain, and probably also these, 

 or another form of zoospore, are dispersed while in the 

 resting stage by wind. 



The pest was identified for me by Mr. Massee as the 

 alga Cephaleurus mycoidea, Karsten (Mycoidea para- 

 sitica, Cunningham), which is known as a destructive 

 parasite on many kinds of thick -leaved trees, in the 

 Straits Settlements, Malay Islands, and Ceylon. It 

 attacks among other trees camellias, tea/ mangosteen, 

 and similar trees. Full accounts of it are published 

 in the Transactions of the Linnean Society, 1880, by 

 Cunningham ; by Karsten in Annales du Jardin 

 Botanique de Buitenzorg, vol. x. p. 24 ; and by 

 Marshall Ward (Trans. Linn. Soc., 1881, vol. ii. p. 87). 



The plant forms a kind of crust, the thallus, on 

 the leaf, and pushes down root-like processes into the 

 tissue of the leaf, destroying it, apparently mainly by 

 using up its water supply. The leaves turn yellow and 

 fall sooner than they should, giving the tree a bare 

 appearance. Many of the boughs are leafless nearly to 

 the top, and the whole appearance of the tree is weak 

 and shabby, with scanty foliage. Some trees in the 

 Botanic Gardens at Singapore were badly affected by 

 this alga, and the treatment of washing them with 

 Bordeaux mixture was tried with marked success. 

 The mixture was syringed on to the trees with a 

 bamboo squirt till the foliage was conspicuously blue. 

 At the next putting forth of leaves it was noticed that 

 the young leaves which came out were not attacked by 

 the parasite, while the trees that were not syringed were 

 as bad as before, the leaves being all spotted with the 

 fungus, and many buds blackened and dead. 



