394 Tricotylous Races. 



several generations. But, at the l^eginning of our cen- 

 tury, we stand only on the threshold on which systematic 

 botany must be raised from a comparative to an experi- 

 mental science. 



The experiments described in the foregoing section 

 (§ 4) cover four generations as a rule, i. e., a selection 

 of tricotylous plants four times repeated, and thrice re- 

 peated for those with apparently the highest values. It 

 may, however, be allowable to suppose that stray un- 

 favorable individuals occurred amongst the selected ones 

 and that a selection of longer duration might possibly be 

 crowned with success. 



In order to determine this point I have, as I have 

 stated above on page 383, continued the experiment with 

 two species, to which I have lately added a third, through 

 about ten generations. I devoted every possible care to 

 the selection and carried it out on as large a scale as 

 could be desired. The result was a genuine progress 

 which amounted in both cases from one or two per cent to 

 a value which reached in the seeds of some rare seed- 

 parents, even as much as 25%. But from the character 

 of an intermediate race with a mean value of 50% the 

 races are still far removed, and every circumstance points 

 to the conclusion that it is simply impossible to reach 

 this by the method (as yet the only available one) w^hich 

 was employed. 



The two plants used in these experiments were Ama- 

 rantiis speciosus and Scrophularia nodosa. The former 

 is an annual garden plant, much in favor on account of 

 its height and its red foliage (Fig. 83) ; the second is a 

 wild perennial species which is very common in this 

 neighborhood. It flowers in its first year and can be 

 easily cultivated as an annual. In the previous section 



