LAVENDER 79 



(c) The short corolla and membranous calyx of the tubular florets, 



(d) The five prominent ribs of the fruit. 



Constituents. Dalmatian insect flowers contain up to 1-25 per 

 cent, of volatile oil, but the toxic principle is a yellow syrupy sub- 

 stance, pyrethrone, which is an ester yielding by saponification 

 pyrethrol. Pyretol and pyrethrotoxic acid, also given as the active 

 constituent, appear to consist essentially of pyrethrone. It is not 

 volatile, and the flowers do not lose their activity when exposed to 

 the air. 



Substances of alkaloidal and glucosidal nature have also been 

 isolated, but our knowledge of them is very imperfect. 



Good insect powder should stupefy common house-flies kept near 

 it within a minute ; less active powders may take as much as twenty 

 minutes to effect this. It should yield about 8 or 9 per cent, of ash 

 and about 10 per cent, of moisture. The quality of the powder is 

 also indicated by the ethereal extract, good closed flowers affording 

 from 7-5 to 10-5 per cent, of yellow extract ; half-closed flowers yield 

 from 6 to 7 per cent., and open flowers from 5 to 6 per cent., while 

 the presence of much stem or leaf is indicated by the greenish colour 

 of the extract. 



Substitutes, &c. Chrysanthemumc occineum, Willdenow, (C. roseum, 

 Weber et Mohr), a native of the Caucasus and northern Persia, yields 

 the Persian (or Caucasian) insect flowers, which were formerly more 

 commonly used than the Dalmatian. The importation has now, 

 however, practically ceased. 



The flowerheads are distinguished from the Dalmatian by the dark, 

 nearly black, colour of the involucral bracts, by the rose colour of 

 the ray-florets, and by the ten-ribbed fruit. They are said to be 

 less active than the Dalmatian. 



Insect powder may be adulterated with powdered leaves and stems, 

 with the powder of other composite flowers, with lead chromate, &c. ; 

 powdered quassia, pepper, aloes, euphorbium, etc., are said to have 

 been found in it. 



Use. Powdered insect flowers and also a tincture prepared from 

 them are used to stupefy smalt insects. 



LAVENDER FLOWERS 



(Flores Lavandulae) 



Source &c. The common lavender, Lavandula vera, de Candolle 

 (N.O. Labiatce), is a small under-shrub indigenous to southern France, 

 Italy, and Spain, but cultivated in this country as a garden plant, 

 as well as on a large scale for its aromatic flowers. It is also extensively 

 cultivated in southern France. 



