INSECT POWDER. 25 



also because it is considered more expedient at this time to place 

 the greatest emphasis upon those diagnostic characters whereby 

 commercial powder may be accurately analyzed microscopically. 



Siedler's (150) (258) morphological description of the Dalmatian 

 flowers, which is quite in detail, may be summarized as follows: 

 The Dalmatian flower stem is 8-sided and very hairy; receptacle 

 slightly arched; involucre consisting of 3 rows of scales, the inner 

 scales lanceolate and about 4 mm. long, the scales of the middle row 

 about 6 mm. long. All of the scales have a flat inner surface, the 

 outer surface being more or less keeled, possessing a scarious margin 

 and covered with hairs. The whitish ray flowers measure about 15 

 mm. in length and 4 mm. in width, 3-toothed at the tip, the middle 

 tooth being somewhat smaller than the other two. The disc flowers 

 are tube-shaped and 5-toothed, possessing the typical Compositge oil 

 glands and containing more or less of the yellow, 3-pored, spiny pollen 

 grains. The fruits of the ray flowers exhibit a different structure 

 from those of the disc flowers, being somewhat flattened on the side 

 lying next to the outer bracts, and possessing 2 furrows, while the 

 inner side has 3. The fruits of the disc florets consist of 4, sometimes 

 6, nerves. A small crown is present on all the fruits. 



Collin (47) designated 3 distinct commercial varieties of Dalma- 

 tian insect flowers : 



1. Closed flowers. — Flower heads, varying from 3 to 7 nma. in 

 diameter, generally furnished with a very short striated peduncle. 

 Bracts, greenish-yellow, closely appressed. Corollas of ligulate 

 florets almost always entire; grayish-white in color, and wrinkled 

 and shriveled over the tubular florets, so as to conceal them almost 

 completely. Very few expanded flowers present; very few frag- 

 ments of corollas, ovaries, or bracts mixed with flower heads. 



2. Half-closed flowers. — Peduncle longer, even 4 or 5 cm. long. 

 Flower heads full, bracts with a yellowish-gray color. Ligulate 

 florets can usually be distinguished; tubular florets still retain their 

 corollas more or less intact. 



3. Oj^en flowers. — Recognized by the size of the flower heads, 

 many of which attain a diameter of from 9 to 11 mm. Usually 

 completely expanded when gathered and hence few of them intact; 

 some ligulate florets destitute of corollas and in many others the 

 corollas of the tubular florets have been separated from the ovaries 

 which remain attached to the receptacle. This variety contains 

 abundant debris of the corollas and ovaries, and therefore is not as 

 choice commercially as classes 1 and 2. He described the various 

 parts of the Dalmatian flower head as follows: Bracts, outermost 

 thicker and shorter than the others; more strongly curved and more 

 pointed at the apex; those from the middle row lanceolate, slightly 

 curved; the inner scales are as long as the middle ones but thinner 



