INSECT POWDER. 31 



of ioclin and 0.2 gram of potassium iodid in 15 cc. of water). Chloral 

 hydrate solution dissolves starch and clears the tissues (about 5 parts 

 chloral hydrate in 5 parts of water). 



DALMATIAN FLOWERS. 



1. Numerous 3-pored, spiny pollen grains (PI. Ill, figs. 3 and 4). 



2. Marginal papilhie and papillae in surface view presenting a 

 "puckered" or 3-cornered appearance (PI. I, figs. 1 and 2). 



3. Sinuous, striated cells of epidermis of ligulate florets (PI. II, 

 figs. 1 and 2). 



4. Toothed fragments of the disc florets (PI. Ill, fig. 2). 



5. Shredded fragments of involucral scales, strongly lignified (PL I, 

 fig. 5). 



6. Attenuated and twisted horizontal cells of T-shaped hairs from 

 the bracts (PL II, figs. 3 and 4). 



7. Occasional strands of stem tissue, much larger than other frag- 

 ments, and usually possessing roughened or fibrous ends (PL I, fig. 6). 



8. on glands from the corolla and fruit. These are very seldom 

 detected in the powder. 



9. Somewhat rectangular patches of sclerenchyma tissue from the 

 fmit, containing numerous diamond-shaped crystals exhibiting a 

 variety of colors under polarized light. Numerous isolated stone 

 ceUs are also often found in powder ground from mature flower heads 

 (PL I, figs. 3 and 4; PL III, fig. 6). 



PERSIAN FLOWERS. 



The diagnostic characters of the Caucasian or Persian flowers 

 {Chrysanthemum roseum) in the powdered form are rather similar to 

 those of the Dalmatian flowers. As already stated, the papillae of 

 the ray florets differ somewhat, and the achene tissues do not contain 

 the crystals characteristic of the Dalmatian flower fruit. The reddish- 

 brown scarious margins of the bracts are often more striking in the 

 Persian powder than in the Dalmatian. Collin (47), who also studied 

 the Persian flowers, has summarized the principal diagnostic char- 

 acters which distinguish them from the Dalmatian flowers. 



SUMMARY. 



Of course, the relative abundance of many of the tissues mentioned 

 depends upon whether the powder is ground from open or closed 

 flowers. Pollen is more abundant in closed-flower powder and 

 sclerenchyma tissues in open-flower powder. The greater part of 

 the pollen of closed or immature flower heads still remains in the 

 closed "buds" or heads, the pollen not having as yet been scattered 

 by the wind. On the other hand, the mature flower heads are practi- 

 cally devoid of any great amount of pollen, but contain the mature 



