24 



BULLETIN 824, U. S. DEPARTMElsTT OF AGRICULTURE. 



Trottner (278) has worked out a method in which the value 

 of an insect powder is determined by estimating the number of 

 pollen grains in 1 milligram of the sample. His results, however, 

 vary greatly, as shown in Table 3, which summarizes all of his re- 

 ported determinations. 



Table 3. — Number of pollen grains per milligram of insect powder. 



Closed flowers of C. cinerarisefoUum pulverized in a mortar 



Do 



Open flowers of C. cinerarisefoUum pulverized in a mortar 



Do 



Do 



Commercial powder ground from closed flowers (Riedel) 



Commercial powder ground from open flowers (Riede!) 



Commercial powder ground from closed flowers (Caesar and Loretz) 



Commercial powder ground from half-closed flowers (Caesar and Loretz) . . . 



Commercial powder ground from open flowers (Caesar and Loretz) 



Commercial powder ground from closed flowers (Scliuchardt) 



Commercial powder ground from half-closed flowers (Schuchardt) 



Commercial powder ground from open flowers (Schuchardt) 



Commercial powder (Apothecary A) 



Commercial powder ground from wild closed flowers (Apothecary B) 



Commercial powder (Apothecary C) 



Commercial powder ground from cultivated closed flowers (Apothecary D) 



Commercial powder (Apothecary E) 



Pulverized closed flowers of P. roseum 



Pulverized open flowers of P. roseum, 



Flores Pyrethri rosei, pulvis No. (Gehe and Co.) 



Flores Pyrethri rosei, pulvis No. 1 (Gehe and Co.) 



Pollen 

 grains in 1 

 milligram. 



2,881 



2,159 



545 



210 



151 



3,066 



158 



2,255 



920 



785 



4,402 



5,544 



1,319 



2,071 



1,235 



1,176 



575 



550 



4,721 



2,264- 



5,741 



3,482 



Morphology of Whole Insect Flowers. 



The flowers usually employed in the production of insect powder 

 or Pyrethrum powder are derived from either the Dalmatian or the 

 Persian insect flowers, botanically known as Chrysanthemum cine- 

 rarisefoUum (Trev.) Bocc. and GhrysantheTnum roseum.'W eh. &M.oh.v., 

 respectively. The Dalmatian flowers compose the greater part of 

 the commercial insect powders, the Persian flowers beiug rarely seen 

 in commerce at the present time. Of recent years, Japanese insect 

 flowers have been coming into the market. According to one 

 authority (24) the form known as Chrysanthemum indicum, with a 

 yellow ray flower, is widely spread through China and Japan, while 

 in the mountains of Hupeh occurs a white or pink rayed form, which 

 has been named Chrysanthemum morifolium. Dr. Henry, who has 

 collected specimens which are in the Kew herbarium, considered 

 these two wild plants the probable progenitors of the cultivated 

 strains. As far as histological characters are concerned, the Japanese 

 flowers can not be distinguished from Chrysanthemum cinerarise- 

 foUum. 



A review of the literature has shown that some little work has 

 been done on the morphology of the whole insect flowers. The 

 descriptions to follow are condensed reviews of the most important 

 articles. They are somewhat abbreviated for the reason that the 

 literature already contains numerous descriptions of the flowers, 



