Arny: Breeding for Atropine 



165 



be throvigh selecti^'e methods, but here 

 again certain difficulties at once arise. 

 Since the characters with which we are 

 working are unseen, the number of 

 individuals that can be placed under 

 observation is therefore limited, and in 

 turn the chances of success are i)roi3or- 

 tionately reduced. 



In establishing a system of selection 

 of belladonna- {Atropa belladonna) at 

 the Mulford Drug Gardens, the effort 

 was made to overcome this difficulty by 

 establishing a correlation between some 

 apparent ]>hysical character and alka- 

 loidal content. If such a correlation 

 could be demonstrated, the advantage 

 of observing thousands of individuals 

 rather than hundreds would be at hand. 



The breeding plot contained 500 

 individuals which were chosen from a 

 lot of several thousand seedlings. The 

 seed from which these plants were 

 grown had been imported from Germany 

 and no previous history of them was 

 known. They were sown in the gree.i- 

 house in January and potted off in the 

 usual manner. Those used for the 

 breeding plot were chosen only because 

 of uniform size and apparent vigor. 

 Some of the features 6f the plant ^vere 

 recorded on a card at the time of set- 

 ting out. These included size in its 

 first and second weeks, and when 

 adult; the blooming date, color, size of 

 leaf and of root, and any other facts 

 which seemed likely to be of interest. 

 The plot contained five rows with 100 

 plants in each row numbered chrono- 

 logically and recorded on individual 

 cards. These plants were examined 

 once each week for the first three weeks 

 and then as often as the data on the 

 cards required. The soil on which the 

 plants grew was a heavy clay loam with 

 a clay subsoil and had received no 

 treatment except a heavy application 

 of stable manure during the winter. 



The leaves were gathered at the 

 usual time — just as the flowers are 

 opening — and enough leaves were al- 

 lowed to remain to mature the fruit 

 pods. The leaves were then air dried 

 on drying racks in bundles correspond- 



ing to the plant from which they were 

 taken, after which they were assayed for 

 alkaloidal content. The error incident 

 to this process was minimized by run- 

 ning the assays in du]:>licate. Of the 

 400 samples, 15 were discarded because 

 too small, or Ijecause they were spoiled 

 in assaying. The alkaloidal content 

 of the remaining samples, expressed in 

 percentages, was as follows: 



The standard of the United States 

 Pharmacopeia is 0.4 atropine in bella- 

 dona, and the average sample found in 

 the markets varies from this minimum 

 to about 0.6. It is evident, then, that 

 nearly 70% of the plants were above 

 the standard in chemical content, and 

 that six of them yielded 1% or more 

 of atropine — a remarkably high per- 

 centage. They were as follows: 



1.020 

 1.000 

 1.100 

 1.230 

 1.030 

 1.039 



Avg. 1.07 



Interest naturally centered on these 

 plants, and a study of the records 

 showed that every one of them was 

 small at the time of harvest, while 

 practically all the plants which yielded 

 .01 or less were large and vigorous in 

 growth. Furthermore, the six high 

 plants all had light stems, while the 

 plants \'ielding . 1 or less had dark stems. 

 These characters were the only ones 

 found which seemed to give a clue to 



2 For an outline of some similar work with belladonna and other plants, see " Breeding Medi- 

 cinal Plants," bv F. A. Miller. American Breeders' Magazine, IV, pp. 193-201. 



