197 



Conclusions. 



The preceding experiments, much abridged as they are hero 

 c-iven show that the toxic principle of the tuba-root kills insects 

 bv acting both as a contact and as a stomach poison. It kills some 

 insects easily, and others with difficulty, but it usually acts slowly 

 and seems to kill by motor paralysis. ^ i wi a ..; 



'■J^he above tests were made under strict control at tlie Agu- 

 cultural Boards Testing Lahoratory of Vienna (Va). ihey put 

 be.vond dispute the efficacy oi^ tuba-root as a plant-insect poison and 

 give it a high place among agricultural insecticides. 



E. Mathieu. 



The Angsana Tree. 



Yet another avenue of the Angsana tree {riovcarpm wMrns) 

 has succumbed to the "disease" that lias already deprived this 

 countrv of some of its finest avenues. It will be reca led by many 

 how these avenues have disappeared one after the other first the 

 one on the sea front in Malacca, then about 1907 one hundred trees 

 ill Penan-- followed by epidemics among these trees at iapali, 

 Kuala Kiii)u, Kuala Lumpor and Taiping. A short while ago 

 the avenue along the sea front at Singapore was also swept away. 

 At the end of May this year (1919) some trees at the end ot an 

 avenue at Tanglin Barracks, Singapore, began to show the well 

 known symptoms. Four months afterwards the 'disease liad 

 advanced considerahly along the Avenue. [)ut not successively tak- 

 inu- toll of every tree for occasionally one was omitted, but so maiiv 

 trees were aft'ected that it was deemed necessary to cut the avenue 

 down A look-out was kept for fungi but there was no opportunity 

 " to make a detailed investigation of the tissues of the trees ihe 

 onlv fungus collected was one of the tropical varieties of / olyporus 

 (Ganodermas) liicidus, sometimes a stipitate form and sometimes 

 more imguiculate. This is interesting as the fungi formerly col- 

 lected from these trees have been Poli/stictm occvcUntaks, b v., 

 Puhislicfus floridanus, Berk., ScUzophjllum commune, In-., and 

 Poilisiidus hirsutns, Fr. So far no fungus has a<-tually been ..!.- 



served in the tissue. ,, . , • n 



'On the otlier hand it is understood that this tree is generally 

 propagated by means of cuttings. Now there are some who liohl 

 that the reason of this tree dying oft' in the m'anner it does is a 

 question of senile decay and not of disease. The theory put for- 

 ward is that the age-of the individual tree must be counted Iroiu 

 the last time its stock was grown from a seed. It is quite like y 

 this mav he manv generations and correspondingly a considerahJe 

 iiumiber'of vears.^ Tt is also to he presumed that the avenues and 

 ..•roups of trees which die olT at the same time, in the same loca- 

 lities are planted from ihe same stock of cuttings an.l w^uld 

 therefore be approximately the same age. In view oi this the 

 following article taken from the Gardens Chronick' \ <•!• l-Wi, 

 Xo. 4111, page 190 is of interest. 



