2 BULLETIN 306, U. S. DEPARTMENT OF AGRICULTURE, 
of the alkaloidal content; then to study the relation of physical and 
chemical characteristics—the influence of environmental factors, such 
as climate and soil—and the fluctuations in the alkaloidal content 
during the growing season. The results of these investigations have 
already been reported.! 
SELECTION OF TYPICAL PLANTS. 
A number of plants were selected which from the data obtained 
in the preliminary investigation showed typical alkaloid-producing 
tendencies. Although only those plants which produce a high per- 
centage of alkaloids are of commercial value, plants of the opposite 
type, namely, those which produce only small quantities, were also 
selected, in order to furnish more comprehensive data on the trans- 
missibility of alkaloid-producing characteristics. An enumeration of 
the individual plants which were selected from the original lot, show- 
ing the alkaloidal content of their leaves at the various stages of 
growth during two seasons, is given in Table 1. 
TaBLE I.—Alkaloids in the leaves of selected belladonna plants during two seasons, at 
Arlington, Va. 
Alkaloidal content (per cent). 
Yield of > 
alkaloids . Stage of growth, 1911. Stage of growth, 1912. 
Plant No. on which 
sleet | 3 , 
was based. = a 24, = i a nA 
- ~~ 3 . — s SS 
#12 Seotaegele | 21218 | 2] Sa 
= 3 — ° = > a 3 a 5 = > 
i op) & ics i <j is mM I FY = < 
= 2 ES i? Rae Te How s2.- 2. 053357} =e 0.526 |0.532 10.200 |0. 414 j...... 0. 292 lo. 3204 SAME ae 0. 406 
3 eS SSS os SE Me gdo<3- = SSeS Zonl eakiel Sosa 450 407 eee .393 | .448 |0.448 |....--. - 426 
75) CS aS Sepia do sees | Ares .348 | .354 | .487 | .425 | .403 |0. 496 Sof Loe th = - 401 
CV ape ee cea eeee [Eee do- = 2 337 285 | .308 588 | .431 | .3 418 334 | .480 483 (0.314 . 406 
1 B45 eae Medium 614 627 | .626 763 | .563 | .639 495 479 | .655 | 7 . 488 .518 
1103 AAs ein Sears aphess = 64 782 693 497 | .584 | .641 767 631 | .685 | .715 | .394 . 638 
7 Ee ee ee Gln 58 | .831 | .832 | .727 | .571 | .704 | .782 | .666 | .646 | .694 | .573 | .672 
Ds fe 2 a eS Se oC) Bee es 596 879 925 711 | .722 | .766 847 747 | .882 | .804 | .558 . 768 
METHOD OF CONTROLLING POLLINATION. 
The flowers of Atropa belladonna are normally cross-pollinated and 
depend principally on insects, such as moths, beetles, and bumble- 
bees, for the transportation of pollen. When insects are excluded 
the flowers fail to develop and soon drop off, which indicates that 
natural self-pollination occurs rarely, if at all. 
In 1911 a large number of flower buds were inclosed in manila bags 
in the hope that close pollination would take place, but none of the 
flowers set seed. However, seeds resulting from the cross-pollination 
of the individual plants enumerated in Table I were collected and — 
planted in flats in the greenhouse at Arlington, Va., in the following 
1 Sievers, A. F. Individual variation in the alkaloidal content of belladonna plants. Journal of Agri 
cultural Research, v. 1, no. 2, p. 129-146, 1913. 
