248 Non-Isolablc Races. 



a pure race with five petals only. For the plants in ques- 

 tion were either weaklings, or exhibited pleiopetalous 

 llowers on other days. I was often able to observe that 

 on many plants six-petalled flowers occur on one day but 

 not on another. The 6-7-petalled flowers are found 

 from the beginning of the flowering period, but the 

 higher figures do not occur till later, as is also known to 

 be the case in other instances of double flowers. 



In 1887 I moved some plants in which the abnormal- 

 itv was well developed, to my garden, v^diere they flowered 

 again in the following summer and set seed. These plants 

 constitute the first generation of my experiment. Since 

 then I have sown seed every year, but only part of the 

 plants, sometimes one-half, sometimes two-thirds, pro- 

 duced flowering stems in the first year, and I have always 

 confined my attention to these, throwing away those 

 which did not bloom during the summer. I have some- 

 times kept some of the best examples of the half race 

 through the winter for secondary experiments, but I shall 

 return to these later on. 



During the period 1889-1892 the second to the fifth 

 generation of the half race were grown in this manner, 

 the extent of the cultures being gradually increased. 

 I always harvested my seed from the most abnormal in- 

 dividuals, which I selected by simply cutting off the 

 flowers with five petals from all the plants. The numbers 

 of these on the individual plants were recorded in some 

 years but not in others. Pollination was left to the 

 bees, but no definite effects of cross-fertilization have 

 been traceable in the results of the experiments. 



The first two years of the experiment (1889 and 

 1890) need only a brief reference. Plants without pleio- 

 petalous flowers or with only very few, were removed 



