INSECT POWDER. 79 



These tests show that the active prmciple can not be wholly acidic 

 or phenolic in nature ; otherwise all would have been extracted by the 

 aqueous sodium hydroxid solution. 



Procedure 3. 



In this procedure the petroleum-ether percolate was not evaporated 

 to dryness, but was first extracted with a saturated aqueous solution 

 of sodium bisulphite to remove aldehydes, if present, and then with 

 1 per cent sodium hydroxid. 



On acidifying the sodium bisulphite extract with sulphuric acid, 

 extracting with ether, and evaporating to dryness, a trace of a 

 sticky varnish was obtained. This had a pleasant odor, gave a 

 somewhat indefinite test for aldehydes, and appeared to be a poly- 

 merization product. The amount obtained was too small for satis- 

 factory testing, but apparently a very small amount of aldehyde is 

 present in the petroleum-ether extract of insect flowers. The sodium 

 hydroxid extract contained a quantity of chlorophyll, and in other 

 respects resembled very closely the sodium carbonate and sodium 

 hydroxid extracts obtained in Procedure 2. 



The residual petroleum-ether solution, after successive treatment 

 with the bisulphite and hydroxid of sodium, was evaporated to dry- 

 ness, and left a sirupy, reddish material similar tx) the residue ob- 

 tained, in Procedure 2. 



Identification Tests on the Materials Isolated in Procedures 1, 2, and 3. 



These extracts were subjected to a number of special tests as out- 

 lined in Mulliken's "Identification of Pure Organic Compounds" and 

 other standard works, the details of which it is unnecessary to repeat 

 here. By means of these tests it has been shown that the petroleum- 

 ether extract of the flowers of C. cineraridefolium, which completely 

 removes all substances of insecticidal action, contains no ketones, no 

 phenols, and no nitrogen-bearing compomid, but that it consists 

 largely of an ester, together with a trace of aldehyde and a quantity 

 of free acids. 



These results harmonize some of the discrepant conclusions reached 

 by previous investigators, especially Schlagdenhaufien and Reeb, 

 who claim that the active principle is an acid, to which they gave the 

 name of pyrethrotoxic acid, and Fujitani, who claims that it is a 

 neutral ester, which he named pyrethron. 



DISTRIBUTION OF THE ACTIVE PRINCIPLE IN CHRYSANTHEMUM 



CINERARI^FOLIUM. 



It has long been known that the flowers of the CJirysantliemum 

 cinerarisefolium possess insecticidal properties. The action of the 

 stems is so slight that they are practically worthless as an insecticide. 

 It has been generally supposed that the buds, or "closed" flowers, 



