AKER TUBA. 23 



with most poisons this is by far the most effective way of adminis- 

 tering them. Owing to the insolubihty of tubaiu, it may be eaten 

 by a fish with impunity. I have seen a fish eat enough to kill a 

 score, without any ill effects ; but when a solution of it in spirits 

 of wine is added to water, although the tubain is at once precipi-)? 

 tated as a bluish-white cloud, still it is then active. Presumably, 

 the fine state of subdivision enables it to be assimilated by aii 

 animal organism. In the sap of the plant it exists as an emul-" 

 sion ; and the sap, having no tendency to coagulate, may be 

 diluted to any extent with water. By this means it becomes an 

 extremely attenuated emulsion. When the roots have becomj^ 

 dry, this only takes place to a very limited extent ; and a solvent 

 is then necessary to bring the tubain into a form in which its 

 poisonous quahties can be applied. 



There appears to be no reason why we should not take the 

 hint from the Chinese market gardeners and apply the poison to 

 the destruction of the many insect pests to which garden and 

 green-house plants are subject. 



From what has been said as to the nature of the substance 

 it will be apparent that the dried roots would be of Httle or no 

 good for the purpose, and either the tubain must, after being 

 extracted from the root, be converted into an emulsion or into 

 some chemical combination easily dissolved in water. By the aid 

 of a small quantity of spirit it may easily be emulsified with soap, 

 which on solution in water presents the poison in an active form. 

 I think it may also be saponified if mixed with oil before it is 

 treated with alkali. My attempts in tliis direction have been only 

 partially successful as yet. In both cases potash, or sofa soaps, 

 would be the most convenient vehicles with which to comf»ine it, 

 as they are so much more readily miscible in water than me soda 

 soaps. The extraction of the poison from the roots in ^ large 

 way would not be costly, as by suitable apparatus the spi:^t could 

 be distilled off and used over and over again ; and doubtless some 

 cheaper method of extraction could be found. The plailfc grows 

 readily in the Straits Settlements. The roots are dug bp from 

 time to time and the stumps and suckers are replanted ^nd soon 

 throw out new roots. The stems also contain the poison, though 

 in not so great a proportion, but still worth extraction. It is 

 probable that the best time of year to harvest the root would be 

 January, as the plant is then at rest and nearly leafless. This is 

 a subject which seems to be well worth the attention of the makers 

 of insecticides and of floriculturists and horticulturists generally.* 



Taiping, 12th March, 1892. 



* See also Kew Gar-dens Report, 1877, p. 43, and Pharm. Journal (3), 

 XVII., p. 5. 



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