On MISC. PUBLICATION 650, U. S. DEPT. OF AGRICULTURE 
by the Inter-American Institute of Agricultural Sciences, to collect 
cuttings of the remaining 4 clones. By that time the introduction 
garden at All-Weather had been abandoned, and the markers which - 
originaliy identified the separate clo es were illegible, missing, or out 
of position. It was therefore necessary to harvest individually the 
275 plants which were in the introduction garden. 
The root svstem of each plant was sent to the Estacién Experi- 
mental Agricola del Ecuador for chemical analysis. Cuttings were 
also sent there, as well as to the Puerto Rico Experiment Station, the 
Estacién Experimenta! Agricola de Tingo Maria in Peru, the Servicio — 
Técnico Agricola de Nicaragua, the Inter-American Institute of Agri- 
cultural Sciences in Costa Riea, the Institute Agropecuanio Nacional! 
in Guatemala. and to the Canal Zone Experiment Gardens, Summit, 
C. Z. After field trials at these stations, any numbers which may 
prove to be consistent high-rotenone producers will be multiplied 
and distributed to commercial growers. 
Quantitative chemical tests for rotenone involve considerable time 
and expense. The analysis of hundreds of root samples, which 
might be necessary in the search for superior planting stock, could be 
very costly to the institutions undertaking the investigations. Pagan 
and White’ have shown that a close and dependable correlation 
exists between rotenone and tota! ether extractives. They believe 
that the easiest and quickest method of evaluating iarge numbers 
of samples with reasonab!e accuracy 1s to determine their total chlo- 
roform extractives. Samples showing real superiority can be segre- 
gated in this way and their true value then determined by quantitative 
tests for rotenone. 
PYRETHRUM 
The flowers of Chrysanthemum cinerariaefolium, known as pyreth- 
rum, constitute one of the most important, as well as one of the 
oldest, recognized. insecticidal materials of plant origin. Dried, pul- 
verized flowers, sometimes called ‘insect powder.” and floral ex- 
tracts have wide application in the control of household, livestock, 
and crop pests. Their toxic action is due to substances known as 
pyrethrins, which usually amount to only 0.8 to 1.3 percent of the 
weight of the dried flowers. 
Although rotenone, nicotine. 1nd certain morganic poisons, as well 
as several svnthetics, including DDT, may be substituted for pyreth- 
rum to some extent, none of them possess as rapid a paralyzing 
effect or “knock-down’’ which makes its action so spectacular. For 
use against insects quickly stunned but not killed by pyrethrum, it is 
blended with other more specifically toxic msecticides. 
Pyrethrum powder and extracts are nonpoisonous to all but 
the relatively small number of human beings who are somewhat 
allergic to it. 
Among the insects most susceptible to pyrethrum are mosquitoes, 
flies, cockroaches, bedbugs, body lice, fleas, Mexican bean beetles, 
7PaGcan, CaLEB, and WuHitr, Davin G. THE EVALUATION OF ROTENONE IN 
Derris ELLIPTICA ON THE BASIS OF TOTAL CHLOROFORM EXTRACTIVES. [Unpub- 
lished manuscript to appear in the Journal of Association of Official Agricultural 
C} Teel 
Uhemists.! 
