i8o 



Heredity and Eugenics 



pangenes would cease to be produced, or at any rate that 

 mutation would cease and the parent species go on as before. 



Genera- 0. rubri- 0. Lamarck- O. scintil- 



tions 0. gigas 0. albida 0. oblonga nenis tana 0. nanella 0. lata lans 



Gen. 8 

 1899 



Gen. 6 

 1897 



Gen. s 

 1896 



Gen. 4 

 1895 



Gen. 3 

 1890-91 



Gen. 2 } 



Gen. i 

 1886-87 



Mutants anu Number observed in O.Lamarck- Mutants and Number 

 different years tana observed in different years 



The mu- 

 tating 

 stem form 



FIG. 68. Diagram showing in condensed form the genealogy of the Oenothera 

 Lamarckiana family and its various mutants during successive years. The num- 

 bers under each type represent the number of new types observed in each year. 



As far as causes were concerned, DeVries had little to offer 

 except the suggestion that the cause was ultimately probably 

 an external one. 



