Aug. IS, 1919 



Derris as an hisecticide 



181 



quantitative; extractions of derris and preliminary tests of 



EXTRACTS obtained 



Five series of quantitative extractions were made as follows : In each 

 series 20 gm. of fine powder of Derris sp. (probably D. elliptica) were 

 exhausted successively with the following five solvents in the order 

 named: First series, petroleum ether, ether, chloroform, alcohol, and 

 water; second series, ether, chloroform, alcohol, water, and petroleum 

 ether; third series, chloroform, alcohol, water, petroleum ether, and ether; 

 fourth series, alcohol, water, petroleum ether, ether, and chloroform; and 

 fifth series, water, petroleum ether, ether, chloroform, and alcohol. No 

 heat was used in any of these extractions. Table I gives the percent- 

 ages of extracts thus obtained. The sequence is shown by the letters 

 a . . . a, b . . . b, c . . . c, etc., beginning with the first extraction 

 in each case. 



Table I. — Successive quantitative extractions of Derris sp. with various solvents, start- 

 ing with a different solvent for each series 



No. of extraction. 



Solvents used. 



^^ethe?™ Ether. Chloroform. Alcohol. Water. 



First. .. 

 Second. 

 Third.. 

 Fourth . 

 Fifth... 



Per cent. 



4.07 a 



4-55 e 



.55d 



.50 c 



. 10 b 



Per cent. 



7. 90 b 



4. go a 



2. 00 e 



.49d 



. 20 c 



Per cent. 

 10. 60 c 



•75 b 

 . 20 a 

 • 50 e 

 .2od 



Per cent. 

 II. 25 d 

 3.60 c 

 3- 30 b 

 2. 59 a 

 I. 10 e 



Per cent. 

 9-75e 

 8.45d 

 5. 00 c 

 5- 05 b 

 10. 80 a 



Attention is called to the following points in the preceding table. 

 From the first extractions it will be seen that petroleum ether is a poor 

 solvent, while the other four may be called good ones; of these four, only 

 alcohol and water can be regarded as economic solvents. Other points in 

 this table will be referred to later. Since the amount of an extract need 

 not necessarily correspond to its toxicity, the following preliminary tests 

 were performed. 



Experience has taught that the honeybee {Apis mellifica h.) is ex- 

 tremely sensitive to stomach poisons ; therefore this insect Was fed small 

 quantities of the foregoing extiacts in order to determine the degree of 

 toxicity of each one. It was furthermore considered desirable to know 

 the effect of heat on the extracts. Consequently five of these extracts 

 were obtained without the application of heat and the other five with 

 the use of it. The following method of procedure was employed: Since 

 all of these extracts, except those obtained with water, have a consist- 

 ency similar to that of thick paste and are not soluble in water, it was 

 necessary to dissolve a small quantity of each in alcohol; therefore 0.4 

 gm. of the petroleum-ether extract was dissolved in 10 cc. of 95 per 

 cent alcohol. The same method was employed for each one of the 

 other nine extracts, including the water extract, so that the effect of 

 the alcohol would be the same in all the tests; and then X cc. of one 

 of these solutions was mixed thoroughly with 5 cc. of honey in a small 



