70 BULLETIN" 824, U. S. DEPAKTMEFT 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 boihng distilled water, but no toxic sub- 

 stances were obtained. No alkaloids were detected. Eymard 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 r61e of insecticide, as he found 

 that the isolated active' principle worked less actively than the 

 original powder. 



•Schlagdenhauffen and Reeb (245), in 1890, distilled 250 grams of 

 the flowers of Pyrethrum 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 



