2 BULLETIN 306, IT. 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. 1 



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 I. 



Table I. — Alkaloids in the leaves of selected belladonna plants during two seasons, at 



Arlington, Va. 





Yield of 

 alkaloids 

 on which 

 selection 

 was based. 







Alkaloidal content (p 



er cent). 







Plant No. 



Stage of growth, 1911. 





Stage of growth, 



1912. 









-d 



§ 

 o 

 o 

 m 



■6 



EH 



1 



o 

 N 





<B 



8? 



> 



& 

 (^ 



•6 

 § 



o 

 CO 



H3 

 EH 



,=1 



1 



.g 



s 



CD 

 gP 

 & 

 > 

 < 



34 



Low 



...do 



...do 



0.335 

 .384- 



0.375 

 .348 

 .285 

 .627 

 .782 

 .831 

 .879 



0.526 

 .277 

 .354 

 .308 

 :626 

 .693 

 .832 

 .925 



0.532 

 .549 

 .487 

 .588 

 .763 

 .497 

 .727 

 .711 



0.200 

 .451 

 .425 

 .431 

 .563 

 .584 

 .571 

 .722 



0.414 

 .407 

 .403 

 .390 

 .639 

 .641 

 .704 

 .766 



0.496 

 .418 

 .495 

 .767 

 .782 

 .847 



0.292 

 .393 

 .366 

 .334 

 .479 

 .631 

 .666 

 .747 



0.320 







0.406 



3 



23 





448 

 341 

 480 

 655 

 685 

 646 

 882 



0.448 





.426 

 .401 



46 



13 



...do 



Medium. . . 



High 



...do 



.337 

 .614 

 .649 

 .558 

 .596 



.483 

 .472 

 .715 

 .694 

 .804 



0.314 

 .488 

 .394 

 .573 

 .558 



.406 

 .518 



12 



.638 



7w 



.672 



6w 



...do 



.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. 



