BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 65 
veloped, depending on the displacement, by the solution being studied, of a 
film of oil spread on a glass plate or a celluloid surface, respectively. 
The study of the relative toxicity of insecticidal materials to goldfish, which 
has as its object the discovery of possible relationships between toxicity and 
chemical constitution upon which future synthetic work can be based, was con- 
tinued throughout the year. The principal experimental study involved the 
determination of the relationship between the optically active and optically 
inactive isomers of dihydrodeguelin. It was found that the optically active 
compound is approximately twice as toxic as the inactive compound. This 
fact has an important bearing on the question of the toxicity of derris, cube, 
and other rotenone-bearing roots, for it is now believed that the deguelin they 
contain is optically active, and hence it may be appreciably more toxic than 
the inactive variety on which all toxicologieal resuits have been based so far. 
A rather extensive investigation of calcium arsenate was undertaken. The 
dependence of the insecticidal and phytocidal properties of calcium arsenate 
on its mode of preparation and finished chemical constitution is not well under- 
stood. The work during the year confirmed the existence of a previously 
suggested definite basic arsenate which can be called tetracalcium arsenate. 
A phase-rule study of the whole system (lime, arsenic acid, and water) was 
also started in the hope that the higher temperature adopted, 62° C. (143.5° F.), 
will result in attainment of equilibrium, a goal that was not reached in a 
similar study conducted several years ago at 35° C. (95° F.). 
A few examples of the miscellaneous analytical and investigational work 
done to aid in various activities of the Bureau indicate the scope or volume of 
these activities. One hundred and Xen samples of miscellaneous insecticidal 
materials, such as calcium arsenate, spray oils, and fluorine compounds, were 
analyzed to check on their suitability for experimental use; 70 samples of 
derris, cube, and other rotenone-containing powders were examined; numerous 
chemical reagents were tested for arsenic for the Bureau of Chemistry and 
Soils, etc. Analyses were made of 3S0 samples of pine wood to which insecti- 
cidal materials had been applied. Of these samples, 199 were from trees 
injected with sodium arsenite, 36 from trees receiving copper sulphate, 96 
from trees to which mercuric chloride had been applied, and 49 from trees 
that received sodium fluoride. These determinations required the develop- 
ment of special methods of analysis,, since the resins in the wood interfered 
with the application of the methods ordinarily used for insecticidal elements 
in organic materials. 
A search was made through the 737.500 United States patents issued during 
the 17-year period from 1917 to 1933, inclusive, and 47 mimeographed lists 
containing the numbers and brief abstracts of those relating to insect-destroy- 
ing devices, insecticide sprayers and dusters, fruit washers, and washing 
procedures, etc., were issued. 
TRANSIT INSPECTION 
Transit inspection was inaugurated at a few strategic railway terminals 
in 1920 for the specific purpose of enforcing the white pine blister rust quaran- 
tine in effect at that time. The value of checking mail, express, and freight 
shipments of restricted plants in interstate movement, and turning back those 
moving to uninfected resrions. was immediately recognized, and the work lias 
been expanded from year to year to cover other railway centers and to include 
enforcement of all Federal domestic plant quarantines. The effectiveness of 
such inspection is shown by the gradual reduction in the percentage of viola- 
tions found. There were 11.9 violations per 1.000 shipments inspected in 1920 
in the enforcement of 1 quarantine, and only 0.0 violation per 1,000 shipments 
inspected in 1934 in the enforcement of 11 quarantines 
Of special interest in the work of the fiscal year I*'.'..! was the finding of 50 
live Japanese beetles at Chicago on July 11 and 12 in a refrigerator car of 
beans arriving from New Jersey. The car had been partially unloaded, and 
careful inspection was immediately made of all hampers available at com- 
mission-merchant houses. Intensive inspection of produce arriving from the 
infested areas was continued throughout the summer by inspectors of the 
Japanese beetle and transit inspection projects, and 88 live beetles and 157 
dead ones were taken from 97 of the 314 cars inspected during the season. Bean 
cars contained the largest number of beetles. Railway agencies were required 
to fumigate or thoroughly clean such infested cars under the supervision of 
an inspector. 
24118—35 5 
