76 BULLETIN 824, U. S. DEPARTMENT OF AGRICULTURE 
The work on insect flowers and stems here reported, in which it is 
shown that the nitrogen content increases with the grade of the 
product, led to a determination of this constituent in the different 
parts of the flower. At the same time a test on insects was made 
to see if the insecticidal effect of these parts was related to the quan- 
tity of nitrogen present. Typical commercial “open” flowers (C. 
cinerarvefolium) were dissected into their principal parts. In most 
commercial samples, the greater number of the flowers have lost 
their disk and ray flowers, and consist only of fruit, receptacles, 
and involucral scales. The fruit amounted, on the average, to 
80.5 per cent, the receptacles to 10.8 per cent, and the involucral 
scales to 8.7 per cent of the whole flowers. Enough disk flowers 
were collected to determine their nitrogen content, but these were 
lacking in so many of the “open” flowers that their natural relative 
proportion could not be determined. Their normal actual per- 
centage by weight, however, is very small. The results of the 
analyses are given in Table 49. 
TABLE 49.—Determination of nitrogen content of insect flowers 
Percentage 
Sample Nitrogen of total 
nitrogen 
. Per cent 
By AIe-+7 OEM: + HOW Ole. 5 ee oes | eee Se eae ee Bee ee ee 1:26 |. 2 eee 
TULL certs trap eee 4 Bonen ape lt NUS hE pry eine | Meee pete ts ae bay feet ae ean a es nee ee ee gg 1. 40 89. 4 
FRECEPtAeleS 2 oF: St Leh aa ES Bese SOREL bie SRE NOSE aE CEs eee Sa ee . 67 5.7 
TESCO To Coes Relea ocd epee ey Seed tendiae se FF Ua aN Sie ath et See Ue IE op t Be ee eh . ol 3.5 
REDS Kc ETOWiCT So ec ee ea ent ree er ne EN cease es go Reich POE eee 68: [Zan ee eee 
The nitrogen in the fruit of five other samples of “open”’ flowers 
was also determined, with the results shown in Table 50. 
Taste 50.—N itrogen in fruit and flowers of insect flower plants 
: Entire ‘‘open’’ 
Fruit flower 
Per cent Per cent 
1. 34 1.31 
SY 1. 22 
1. 34 
1. 24 125 
1. 26 1. 25 
These results show that the fruit from commercial samples of 
‘‘open’’ flowers contains about 90 per cent of the total nitrogen. 
I. W. Scott and W. S. Abbott, of the Bureau of Entomology, 
conducted practical tests on roaches to determine the relative insecti- 
cidal strength of different parts of the finely powdered flowers. The 
roaches were dipped in the powder until all parts of the body were 
covered with it, and then placed in 8-ounce bottles, 1 insect to a 
bottle, 10 insects being used in each test. All of the insects were 
allowed ventilation, but no food or water. The average of the 10 
tests for each powder is given in Table 51. 
