EFFECTS OF SELECTION ON ALKALOIDS IN" BELLADONNA. 



January. Late in April, when the plants from these seeds were about 

 3 or 4 inches high, they were transplanted to the field. 



In 1912 a second attempt was made to secure seeds from close- 

 pollinated flowers, and in order to insure fertilization the pollen was 

 transferred to the stigmas by hand before the flowers were inclosed. 

 The method of bagging the flower buds used in the previous year 

 again proved ineffectual, since a species of aphis bred in the bags in 

 great numbers and destroyed the young plant tissues. Seeds were 

 obtained from a number of selected plants which had been inclosed in 

 cheesecloth cages, but even within those cages the aphides often 

 multiplied to such an extent as to injure the plant. The seeds from 

 these plants were sown in flats in the greenhouse and the seedlings 

 therefrom transplanted to the field, the same as in 1911. 



FIRST-GENERATION PLANTS FROM CROSS-POLLINATED PARENTS. 



The plants from the seed of the cross-pollinated selected individuals 

 in 1911 were transplanted to the field late in April. There were from 

 6 to 15 individual plants from each parent. These plants made a 

 fairly rapid growth and by midsummer were in full bloom, but the 

 growth they had made was not sufficient to make possible a picking 

 from each individual plant. A collective sample was therefore se- 

 cured from each set of individuals derived from the same parent. On 

 August 30, when the berries were partially ripe, the second picking 

 was made. In picking these samples care was taken to get leaves 

 from all the individuals, so that the results of the assay would indicate 

 as nearly as possible the average percentage of alkaloids in the leaves 

 of the individuals. Table II shows the results of the assays. 



Table II. — Alkaloids in the leaves of first-generation belladonna plants grown from cross- 

 pollinated selected parents at Arlington, Va. 



Parent plant. 



Alkaloidal content (per cent). 



Parent plant. 



Alkaloidal content (per cent). 



No. 



Yield 

 of al- 

 kaloids. 



First 

 picking. 



Second 

 picking. 



Average. 



No. 



Yield 

 of al- 

 kaloids. 



First 

 picking. 



Second 

 picking. 



Average. 



34 



3 



13 



Low 



....do.... 

 Medium 



0.524 

 .479 

 .640 



0.693 

 .518 

 .859 



0.609 

 .498 

 .750 



12 



7w 



6w 



High.... 



do 



....do.... 



0.650 

 .617 

 .805 



0.882 

 1.063 

 1.282 



0.766 

 .840 

 1.043 



From Table II it is evident that these first-generation plants dis- 

 played largely the characteristic of the parent plants as regards alka- 

 loid production. Plants 7w and 6w merit special attention, their 

 leaves containing more than 1 per cent of alkaloids. 



The following season, 1913, these plants were large enough to fur- 

 nish samples from each individual, and pickings were made at four 

 stages of growth during the season. The first picking was on May 6, 

 before flowering; the second on May 23, when the plants were in full 



