- 31 - 
There are also available apparently large amounts of a different t ,T pe 
of cube which has a lower .rotenone content, usually 3 percent to just 
under 5 percent, but with % go fl anoiint of ether extractives, fron 
13 percent to as high as 22 percent. The indications are that this 
nay be about as effective and satisfactory as the first type for use 
in agricultural dusts but more conplete information on it is badly 
needed. " 
Hoycr and Leonard (205) in 1936 proposed an "Index ">f Relative Toxicity" 
for the evaluation of dcrris and cube. This figure is the ratio: percent total 
ether extractives divided by percent rotcnonc. Examples arc giver, of rotonono- 
bearing roots whose index of relative toxicity varies fron 2.5 to 4.5. The 
total ether extractives in dusts standardized to a 0.75 percent rotenone con- 
tent, made by diluting these dcrris powders with clay, talc or sulphur, 
ranges fron 1.87 percent to 3.38 percent. The authors conclude; (1) "The 
percentage rotenone alone is not an accurate index of toxicity; (2) Roots hav- 
ing the greatest relative amounts of ether extractives are the best; (3) 3y the 
use of the Index of Relative Toxicity the value of several roots, regardless 
of species and source ;f origin, nay be put on the sane basis for comparison." 
Jones and Smith (230) in 1936 proposed the following formula to ex- 
press the approximate toxicity of cube as determined by chemical analysis-: 
Toxicity value = percent rotenone +0.4 (total extractives - rotenone); 
total extractives may be determined with acetone, benzene or carbon tetra- 
chloride. This formula expresses fairly well the relation between toxicity 
to houseflies (determined by the Campbell turntable method) ana chemical 
analysis of 5 samples of cube containing fron 0.8 to 12.1 percent actual ro- 
tenone. 
Attention is called in the Bureau of Entomology and Plant Quarantine 
News Letter (169) for February, 1936, to Goodhue's (J^ur. A. 0. A. C. 19:118) 
improvement in the Gross-Smith colorimetric method for rotenone. The method 
is suitable for the analysis of spray residues of derris and cube. 
Robinson (356) in 1935 called attention to the difficulty of estimat- 
ing the rotenone content of haiaris grown in British Guiana by the methods 
of Jones, Calm and Boon, and of Tattersfield and Martin, and proposed a mod- 
ification of the carbon tetrachloride method. 
Beach (23) in July, 1936, described a method of extracting rotenone 
from 20-mcsh powdered cube root with chloroform at room temperature Roten- 
one is determine:'', in an aliquot of the filtrate as the carbon tetrachloride 
solvate in the usual way, 
Begtrup (25) in 1937 described a method in which 100-mesh cube powder 
packed tightly in an ordinary funnel is extracted ~oy pouring toluene through 
it 6 times at room temperature. Rotcnnne is weighed as the carbon tetra- 
chloride solvate. 
Jones (219) in 1936 reported, on the optical rotatory power of extracts 
of derris and cube roots. His conclusions were: 
