ADULTERATION OF INSECT POWDER. 



9 



fPl. II, fig. A). Dnrrant (10) found cJifficiiltv in detecting daisy in 

 genuine insect powder, and Beringer {2) could detect.no difference 

 microscopically between the two powders. 



However easily the hairs Schrenk has referred to may be detected 

 on the unground involucral scales, their presence is very difficult to 

 establish when the scales are pmvdered. Apparently the hairs are 

 very fragile and become readily broken up in the process of grinding. 

 The achenes of ('hrijsantJtcinniii ciiicraiifrfoliinii and ChrijsantJie- 

 iiniiii Leucaiifhriiiiiiii are strikingly different in the powdered form. The 

 achene tissues of the Dalmatian flowers (C. cineraria'foJiiiiii) are cha'r- 

 acterized b}' the numerous crystals, which exhibit a variety of colors 

 under polarized light. On the other hand, the achene tissues of the 

 daisy flowers (C. Leucaiifhemum) exhibit no such crystals, but con- 

 tain a notable amount of a brownish-red material, the location of 

 which is readily demonstrated in a cross-section of the fruit. In 

 a cross-section of the achene, crescent-shaped structures, correspond- 

 ing to each of the ten ribs, stand out very distinctly (fig. 1). 



When the daisy flower heads are powdered, this brownish-red ma'- 

 terial contained in the crescent-shaped structures breaks ujj into ir- 

 regular, angular fragments, sometimes attached to the surrounding 

 tissues, and sometimes separated from them. These fragments assume 

 a deep, brownish-red color when the powder is heated in a solution 

 of chloral hydrate in Avater about 1:1. 



Aside from this dark brown material, a portion of the tissue from 

 the white ribs of the daisy achene is another diagnostic character. 



The outer portion of the 

 rib consists, in radial sec- 

 tion, of Avhat are apparent- 

 ly epidermal cells. They 

 ai)pear to have a palisade- 

 like arrangement, consist- 

 ing ol' narrow. thick-walled 

 cells packed very closely 

 together (IM. II, flg. 2). 

 riiis tissue, wliich invaria- 

 ily occurs in the daisy 

 jiowder in the form of ra- 

 dial sections, serves as an- 

 other means for detecting 

 its i>resence in genuine in- 

 sect ])owder. 



Experience gained in 

 the comparative study of 



Fig. 1. — Cross-section of daisy achene (illustrating crescent- ^^ laro'C nUIllber of SaUlplCS 

 shaped structures). * 



uround from insect flow- 



