INSECT POWDER. 19 
In testing the action of insect powder against various insects Smith 
(268) and many other entomologists used different brands of com- 
mercial insect powders. Their results were comparative, as they 
were without samples of known purity, and their experiments are 
without value in showing the presence of adulterants. 
MICROSCOPICAL METHODS 
There has been much divergence of opinion as to the value of a 
microscopical examination of an insect powder in determining its 
genuineness. For instance, Jelliffe (748) concludes that “the 
microscope is the only possible means for detecting the presence of 
pbiidéted stems in insect powder.’”’ On the other hand, Beringer 
(29), after examining genuine insect powder and the powder made 
from the flowers of the Hungarian daisy, says, “‘ Microscopically no 
difference could be detected between the two powders.” Howie 
(139) states that he finds chemical methods more exact and trust- 
worthy than microscopical ones for detecting added fustic, chrome, 
and turmeric. Again, in discussing Kirkby’s (156) paper, he says 
that he has little faith in microscopical observation for ascertaining 
the value of an insect powder, the physiological test with the black 
beetle being the best. 
For recognizing the presence of certain adulterants, as for instance 
starch or starch-bearing materials, the microscopical examination 
is of great value, but in the powdered state flowers of certain of the 
Composite closely allied to Pyrethrum are so similar to insect flowers 
as to render their detection difficult. Again, although an adulterant 
can usually be detected qualitatively by the microscope, no exact 
quantitative method has as yet been devised for its determination. 
Trottner (278) has worked out a method in which the value of 
an insect powder is determined by estimating the number of pollen 
erains in 1 milligram of the sample. His results, however, vary 
greatly, as shown in Table 38, ae summarizes all of his reported 
determinations. 
TaBLE 3.—Number of pollen grains per milligram of insect powder 
: Pollen 
Product grains in 1 
milligram 
Closed HOWOLS OL Cs CUeErane-cjouwm PUlVerized 1n.a. mortar: 2. el ee eee 2, 881 
eee mee oe eel = SBR at We eyes SE SAR os Dee he Dah Ae a ie eh 2, 159 
Open flowers of C. cinerarizfolium pulverized in a mortar____________________-.-__---_-___-.- 545 
TOE sae Se SO eR Ee a Se a, SPC Tee Pad ek eae cA hee epee oe 210 
PO ie 2 ee ar ce es st a SO i alge ere eb cyl ec aM Natl ie ar te Repel Malt 4B cl 151 
Commercial powder ground from closed flowers (Riedel)___.._______________~_-_--_--------_- 3, 066 
Commercial powder ground from open flowers (Riedel)_____________..____.___-___---_----_-- 158 
Commercial powder ground from closed flowers (Ceesar and Loretz)_______________-_-___-___- 2, 255 
Commercial powder ground from half-closed flowers (Czesar and Loretz)___-_________________- 920 
Commercial powder ground from open flowers (Ceesar and Loretz)____-______-____--_------- 785 
Commercial powder ground from closed flowers (Schuchardt)______________----___-_--------- 4, 402 
Commercial powder ground from half-closed flowers (Schuchardt) -________------------------ 5, 544 
Commercial powder ground from open flowers (Schuchardt)_-________-_-_------------------- 1,319 
WGonmoecren powder CApothecary; Aye sik Be Ee aoe eS es 2, 071 
Commercial powder ground from wild closed flowers (Apothecary B)-_----------------------- 1, 235 
Wormtnerem now GersGADOtneCany: ©). ae ee ee ee 1, 176 
Commercial powder ground from cultivated closed flowers (Apothecary D)_-_-_------------- 575 
WGMTHETE DOWEL CA POLRCCATY! Bint tae SRL SUE al ge Nee sf eee 550 
eR Zee OSCULMOWEIS ONE) TOSEI Ua otEs se See ek Eo Nee ee cles Waele, bo ee ee 4,721 
RAMEE REZ CA OIs id OWLS Ole E> GOS Cll Moet 8 oe eS en Mee oe Sey eo a 2, 264 
Hiareseearcvnrlrosel, pulvis, No.0 (Gehe and Co.) 2. . 222 to es 8 ea ee ee 5, 741 
Plores Pyretiir rosel, pulvis ‘No. 1 (Gehe and Co,):.-.-_ L220 2ibs_ leet eee 3, 482 
