46 HEREDITY 



But the progeny of each of the original nineteen 

 parents had been kept separated, so that the general 

 population could be separated into its nineteen con- 

 stituent pure lines. On examining these nineteen pure 

 lines it was found that each had a distinctive average 

 size of seed, and a distinctive standard deviation. The 

 degree of variability in each pure line was considerable, 

 so that it would have been quite impossible to say, 

 with regard to a single seed taken at random, what 

 particular pure line it belonged to. Indeed, differences 

 within a single pure line were often much larger than 

 the difference between the average sizes of two distinct 

 pure lines. Variability within each pure line approached 

 the normal type ; the average weight varied from 

 351 to 641 milligrams, and the standard deviation from 

 64 to 109 milligrams. 



In each pure line the seeds were sorted into different 

 sizes, and the lots obtained were grown separately. 

 The progeny from each size of mother-seed were after- 

 wards weighed in order to determine whether the 

 variation in size within the pure line had been inherited. 

 With " Line B " the following results were obtained : 



Size of "Mother" Seeds. 

 350-400 mg. 

 450-500 

 500-550 

 550-600 

 600-650 

 650-700 



Average Size of Offspring, 

 672 mg. 

 535 

 570 



565 



566 

 555 



This indicates that variations in the weight of seed, 

 within the pure line, are not inherited ; generally 

 speaking, the progeny of the small mother-seeds were 

 just as heavy as those grown from the largest. 



A similar experiment was carried out with all the 

 nineteen pure lines, with the same result. Moreover, 

 experiments with the other characters dealt with 

 yielded exactly similar results. In brief, the individual 

 characteristics of the parent did not tend to be repro- 



