70 BULLETIN 824, U. S. DEPARTMENT OF AGRICULTURE. 
5.60 grams ether extract. This was dissolved in alcohol and treated 
with silver nitrate, which precipitated the fatty acids as silver salts, 
while the silver resinates remained in solution. The ether extract 
was in this manner shown to consist of 3.80 grams fatty bodies and 
1.80 grams resinous matter. Insects placed upon a piece of paper 
impregnated with this resinous matter manifested extreme agitation 
and died in about 5 minutes. After exhaustion with ether, the 
insect powder was successively extracted with 95 per cent alcohol, 
cold distilled water, and boiling distilled water, but no toxic sub- 
stances were obtained. No alkaloids were detected. Eyniard con- 
cludes that the toxic principle of Pyrethrum is found in the part 
soluble in ether, and more especially in the resin. However, it is his 
opinion that several factors unite in the role of insecticide, as he found 
that the isolated active principle worked less actively than the 
original powder. 
Schlagdenhauffen and Keeb (245), in 1890, distilled 250 grams of 
the flowers of P}Tethrum in a current of steam, collecting 750 grams 
of distillate. After filtering through a wet filter, the distillate was 
extracted with ether, the ethereal solution separated, filtered, and 
evaporated at a temperature not exceeding 30°. A few drops of a 
green oil which was toxic to insects were thus obtained. No alkaloid 
was present in the oil. The aqueous part was acid, but had no 
injurious effect upon insects. The authors obtained an acid which 
was toxic to insects, by exhausting with alcohol acidulated with 
hydrochloric acid, drying, exhausting with ether, shaking the ethe- 
real solution with ammoniacal water, evaporating to dryness, again 
taking up in water, and filtering. The filtrate contains the am- 
monium salt of the toxic acid. This acid was also obtained by 
extracting with alcohol, neutralizing exactly with a solution of 
potassium hydroxid, evaporating gently to dryness, taking up in 
water, filtering, and treating the filtrate with a solution of tartaric 
acid, and extracting the liberated acid with ether. This toxic acid 
the authors call pyrethrotoxic acid. Injected into guinea pigs, this 
acid produced its action in 2 perfectly distinct stages. In the first, 
an excitation was produced, being more or less pronounced according 
to the proportion of matter administered; in the second stage, on 
the contrary, a complete prostration was produced, accompanied 
always with paralysis of the lower extremities. 
Thorns (275), 1890, extracted 10 kilograms of best "closed" 
Dalmatian flowers with 55° petroleum ether for 7 days. Evaporated 
in vacuo, he obtained 230 grams of a greenish-yellow extract which 
had the characteristic odor of insect powder. This extract contained 
many crystals and was of a waxy consistency. By solution in alco- 
hol and again evaporating, a yellow wax, melting point, 54°, was 
obtained. By pouring the alcoholic solution into water and setting 
