26 BULLETIN 824, U. S. DEPARTMENT OP AGEICULTURE. 



and spatulate in shape. All scales thickened in the center, grad- 

 ually becoming thinner toward the margin, which is scarious and 

 transparent. Ligulate florets with 3 teeth at the apex, central tooth 

 smaller than the other two. Calyx with fringed or slashed margin. 

 Ovary possesses 5 projecting ridges. Tubular floret corolla rather 

 deeply 5-toothed. Peduncle channeled and hairy. 



The Persian (186) or Caucasian insect flowers {Chrysanthemum 

 roseum) differ somewhat from the Dalmatian flowers, and will be 

 but briefly described. The flower heads somewhat resemble those 

 of the Dalmatian variety, but are a little smaller. Ray florets, a 

 reddish-purple tinge; involucral scales, dark and with reddish-brown 

 edge. Fruits usually 10-ribbecf. Involucre not as hairy as that of 

 the Dalmatian flower. 



SUMMARY. 



Dalmatian flowers. — Involucre: Imbricate and campanula te; scales 

 matted with hairs; individual bracts slightly thickened or keeled, the 

 inner bracts becoming thinner and more chaffy or scarious at the 

 margin. 



Ligulate florets : Yellowish-white or of a light straw color; pistil- 

 late; apex 3 -toothed, the middle tooth usually being shorter thaji 

 the other two. 



Disc florets: Perfect, deeply 5-toothed, and yellowish in color. 



Achenes of ligulate florets: Distinctly 5-ribbed; rather more flat- 

 tened and curved than achenes of disc florets and somewhat larger; 

 possess small-toothed crown. 



Achenes of disc florets: Distinctly 5-ribbed; not as curved or flat- 

 tened as those of the ligulate florets; somewhat smaller; possess 

 small-toothed crown. 



Persian flowers. — Involucre: Imbricate and campanulate; scales 

 almost glabrous; hairs numerous in depression at juncture of peduncle 

 and receptacle; scales dark and bordered by a distinctly reddish-brown 

 edge; inner scales more scarious than outer ones; appear to be 

 more densely fibrous than those of the Dalmatian flower. 



Ligulate florets: Tinged a rather purplish-red; pistillate; apex 3- 

 toothed, middle tooth often somewhat longer than the other two. 



Disc florets: Perfect, deeply 5-toothed. 



Achenes of ligulate florets: Usually 10-ribbed; more flattened and 

 curved than achenes of disc florets and somewhat larger. 



Achenes of disc florets: Usually 10-ribbed; not as curved or flat- 

 tened as those of the ligulate florets; somewhat smaller. 



Microscopical Characteristics of Insect Powder. 



Before taking up the general plan followed by the authors in the" 

 microscopical examination of a conmaercial powder, the most impor- 

 tant work done by other investigators will be reviewed briefly. 



