i9i6] DeVRIES— DIMORPHIC MUTANTS 269 



The percentage of typical individuals in the second generation 

 is about the same as for 0. cana (25 and 53 per cent), for 0. pal- 

 lescens (35 per cent), and for 0. Lactuca (43 per cent). From this 

 it may be concluded that the 4 races have the same hereditary 

 constitution which, moreover, is the same as in 0. scintillans. 



The next year (1915) I cultivated a third generation of the 

 second mutant of the table (mutant no. i from lata). The har- 

 vest had been small, as in the previous generation, and only 33 

 seeds germinated. Of these 9 were liquida, i was pallescens, i 

 oblonga, and the others Lamarckiana. All of them have flowered. 

 The percentage for liquida was 27, or about the same as in the first 

 generation. Moreover, I have sown for each of the 3 cultures of 

 1 9 14 the seeds of one or two typical individuals, and also for each 

 of them the seeds of two of the atavistic or Lamarckiana type. 

 These 6 last sowings contained 150-300 seedlings each, together 

 13 1 1, of which 8 were mutants (3 oblonga, 4 lata, i cana); the 

 remainder were all of the Lamarckiana type, no liquida occurring 

 among them. The seedHngs of the 4 liquida specimens gave the 

 results indicated in table VIII. 



TABLE VIII 

 Third generation of 0. mut. liquida 



The countings were made in June and July in the boxes in 

 which the seeds had been sown; the plants were all young rosettes 

 with leaves 15 cm. long in the Lamarckiana type, and 6-10 cm. 

 long in the liquida specimens. The differences were clear and sharp. 

 The table shows that the spHtting was almost exactly the same in 

 the third as in the second generation. 



Dimorphic races do not seem to be rare among the mutants 

 of 0. Lamarckiana, and have been observed to spring also from its 



