I So 



Heredity and Eugenics 



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

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



Genera- 0. mbri- 0. Lam^irck- 0. scintil- 



\.\"n~ 0. .i;i,i;(i5 0- alb hi a 0. ohlonga nervis iaiia O.nuticlUj 0- laid lans 



Gen S 

 iSgg 



Gen. 7 

 iSg.S 



Gen. 

 1S97 



Gen. 5 

 i8g'j 



Gen 

 iSg, 



' / 



Gen. 3 

 iSgo-gi 



Gen 2 



iSSS-Sg 



Gen. I 



18SO-S7 



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



different years laiia observed in different years 



Tlie mu- 

 tating 

 stem form 



Fig. 68. — Diagram showing in condensed form the genealogy of the Ocnotliera 

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

 bers under each ty[3e rcjiresent 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 C-xternal one. 



