Production of Double Flowers 497 



A far more important principle is that of the 

 hereditary percentage, already discussed in our 

 lecture on the selection of monstrosities. In 

 our present case it had to be applied only to the 

 six selected plants of 1895. To this end the seeds 

 of each of them were sown separatel}^, the ray- 

 florets of the terminal heads of each of the 

 new generation were counted, and curves and 

 averages were made up for the six groups. 

 Five of them gave proof of still being mixtures 

 and were wholly rejected. The children of the 

 sixth parent, however, formed a group of uni- 

 form constitution, all fluctuating around the de- 

 sired average of 21. All in all the terminal 

 heads of over 1500 plants have been subjected 

 to the somewhat tedious work of counting their 

 ray-florets. And this not in the laboratory, but 

 in the garden, without cutting them off. Other- 

 wise it would obviously have been impossible to 

 recognize the best plants for preservation. I 

 chose only two plants which in addition recom- 

 mended themselves by the average number of 

 rays on their secondary heads, sowed their 

 seeds next year separately and compared the 

 numerical constitution of their offspring. 

 Both groups averaged 21 and were distributed 

 very symmetrically around this mean. This re- 



