INSECT FLOWERS 



675 



Powder. (Fig. 297.) Dalmatian powder, light yellowish-brown; 

 Persian powder, light brown; fragments of the ovary, corolla and 

 flower stalk contain brownish resin secretion canals, the contents 

 of which are soluble in hot alcohol, colored yellowish upon the addi- 



ep 



tep 



FIG. 297. Flores Pyrethri (Insect flowers): sc, stone cells; ep, upper epidermis 

 of a bract; h, h, non-glandular hairs of bracts; ept, papillae on the upper 

 surface of the ligulate corolla; St, St', loose parenchyma of the ligulate cor- 

 olla; g, a trachea of a bract with annular thickening; S, tooth of a tubular 

 floret, some of the cells of which contain rosette aggregates of calcium 

 oxalate; ep', epidermis of the under surface of a ligulate corolla; P, section 

 of pappus showing some of the lignified cells, some of which contain mono- 

 clinic prisms as shown at rh; pa, parenchyma of a bract; Fr, somewhat 

 thickened, porous cells of the pericarp of the achenes; D, glandular hairs 

 found on the wall of the ovary; po, pollen grains; iep, cells of the involucre 

 between the bracts. After Hanausek. 



tion of a solution of potassium hydroxide, which fades on the addition 

 of an excess of acetic acid. Furthermore, upon the addition of either 

 sulphuric acid or hydrochloric acid, the contents are colored yellow- 



