INSECT POWDER. 27 



Collin (47) has condensed the descriptions of the diagnostic charac- 

 ters for the various parts of the flower head of Clirysanthemum cine- 

 rarispfoliwm, which ma}^ ])c summarized as follows: 



Fragments of the bracts: Epidermis striated and provided with 

 numerous stomata, T-shaped hairs, and oil glands; under the epidermis 

 of the central part there is a very characteristic fibrous hypoderma; 

 the margins are very thin, and bear numerous T-shaped hairs. 



Corolla of the ligulate florets: Upper (inner) epidermis character- 

 ized by being papillose over the whole surface, and by the sinuous 

 striated cells of the lower (outer) epidermis. 



Corolla of the tubular florets: Epidermis papillose near the apex 

 but smooth over the remainder of the corolla, the latter portion con- 

 sisting of regular cells containing rosette crystals of calcium oxalate. 



Calyx of the tubular florets: Tissue of the calyx strengthened by the 

 presence of numerous elongated, lignified cells. At the junction of 

 the calyx with the ovary there is a disc composed of large, very irregu- 

 lar cells, with thick, lignified, pitted walls. Many of these cells contain 

 prismatic crystals of calcium oxalate, one in each cell. 



Ovary: Epidermis of the intercostal depressions is characterized 

 by the presence of numerous oil glands and clinorhombic crystals. 

 There is a lignified hypoderma similar to that of the lower part of the 

 calyx. Walls of the ovary contain very large ducts filled with a brown 

 granular secretion. 



Anthers: Filaments consist of regularly arranged square cells; pol- 

 len grains, tubercular, having 3 pores. 



Style: Cells of apex papillose; those of the stigma present a scale- 

 like arrangement. 



Receptacle: Characterized by large, rounded, pitted cells. 



Peduncle: Debris furnished with T-shaped hairs and oil glands. 



Hart (119) has called particular attention to the large number of 

 translucent particles which he found in the ray florets. They oc- 

 curred in every part of the flower head, except the bracts, but were 

 most numerous in the ray florets. When treated with osmic acid 

 they darkened very slightly, if at all, but when treated with an 

 alcoholic solution of alkannin they turned red, which proved them to 

 be resinous. 



Schrenk (249) observed that the stems of the flower heads of Clirys- 

 anthemum cinerarisefolium (furnishing the Dalmatian flowers) consist- 

 ed of collenchyma tissue which exceeded in amount the bast and 

 woody tissues of the fibro-vascular bundles. Therefore fragments of 

 collenchyma cells would be present in proportion to the amount of 

 stems present, being very sparse in a good powder. The use of chlor- 

 iodid of zinc was recommended for their detection. Schrenk foimd 

 the scales of the involucre to be stiffened on the outer side and on 

 both sides of the midrib b}'' a coherent layer of sclerenchyma cells, 



