10 



BULLETIN 306, U. S. DEPABTMENT OF AGBICTJLTUBE. 



From Tables IV and V it becomes apparent that during both the 

 first and second seasons these first-generation plants display very 

 markedly the characteristic of the parents as regards alkaloid pro- 

 duction. Thus, in 1913 the average percentage of alkaloids found 

 in the plants from the original parent 6w and the parent 7w, which 

 were selected for high alkaloid-producing tendencies, was 0.640 arid 



I 



23 C» 



46(6) 



7MU 



7W(oj 



6W(6) 



6W(a) 



Fig. 5. — Diagram showing the alkaloidal content of the leaves of first-generation belladonna plants from 

 close-pollinated and cross-pollinated selected parents at two stages of growth during the first season, 

 1913. The percentages indicated represent the average of all the individuals from each parent plant: 

 a, Plants from close-pollinated parents; 6, plants from cross-pollinated parents. 



0.615 per cent, respectively. On the other hand, the averages from 

 the plants 23 and 46, which were produced from parents of the 

 opposite tendencies, are 0.408 and 0.428 per cent, respectively. Again 

 the following year we find the average of plants 6w and 7w to be 

 0.814 and 0.773 per cent, respectively. Lot 46 was not picked that 

 year, but lot 23 averaged 0.497 per cent. 



If will be seen from the tables that the effect of close pollination 

 as compared with cross-pollination is not as great as would be expected. 

 In the case of 6w the plants from close pollina- 

 tion are on the average 0.091 per cent richer 

 than those from cross-pollination in 1913, and 

 0.042 per cent richer in 1914. The 7w plants 

 show a difference of 0.001 per cent in favor of 

 cross-pollination in 1913 and a difference of 

 0.062 per cent in 1914. Figures 5 to 8 graphi- 

 cally illustrate these conditions. Sufficient 

 information has not been obtained to indicate 

 with any degree of certainty the influence of 

 cross-pollination and close pollination on the 

 tramsmissibility of the alkaloid-producing char- 

 acteristic. As a possible explanation of the 

 large percentage of plants with high alkaloidal 

 content among the first-generation plants secured from cross-polli- 

 nated selected parents, Dr. W. Van Fleet, of the Office of Drug- 

 Plant and Poisonous-Plant Investigations, has prepared the following 

 statement : 



The arrangement of anthers and stigma in the belladonna bloom and the respective 

 periods of their maturity and receptivity are such as to fit the plant in a high degree 



Z3(t>) 46(b) 7IVC6J 7W) 6^(6) 6)Y(tl) 



Fig. 6.— Diagram showing the 

 average alkaloidal content of 

 all the individual belladon- 

 na plants from each parent 

 for the first season, 1913: 

 a, Plants from close-polli- 

 nated parents; 6, plants 

 from cross-pollinated par- 

 ents. 



