160 



EVOLUTION AND ANIMAL LIFE 



family, described above, namely, 0. lata, cUiptica, nanneUa, mibri- 

 nervis, and also two new species, 0. spatulata and leptocarpa. 



"In the lata family, only 

 female flowers are produced, and, 

 therefore, in order to obtain seeds 

 they were fertilized with pollen 

 from other species. Here also ap- 

 peared some of the new species, 

 already mentioned, namely, al- 

 bida, nannella, lata, oblongata, ru- 

 brinervis, and also two new species, 

 elliptica and subovata. 



"De Vries also watched the 

 field from which the original forms 

 were obtained, and found there 

 many of the new species that ap- 

 peared under cultivation. These 

 were found, however, only as 

 weak young plants that rarely 

 flowered. Five of the new forms 



were seen either in the Hilversam field, or else raised from seeds that 

 had been collected there. These facts show that the new species are 

 not due to cultivation, and that they arise year after year from the 

 seeds of the parent form, 0. lamarckiana." 



FIG. 98. Stamens of a hybrid willow, 

 Salix auritax purpurea, showing dif- 

 ferent degrees of varying. 



FIG. 99. A branch of a Japanese tree, Cryptomeria japonica, showing an atavistic 



variation. (After de Vries.) 



As to this we may observe: It has long been known that 

 individual variations of an extreme degree sometimes occur, 



