246 



GENETICS IN RELATION TO AGRICULTURE 



TABLE XXXIX. RESULTS OF VARIOUS MATINGS OF rubrinervis (R.) AND nanella (N.} 



AND THE FORMS PRODUCED FKOM SUCH MATINGS (compiled from 



de Vries, "Gruppenweise Artbildung") 



parent that the phenomena exhibited, although complex, are very orderly; 

 but no very consistent Mendelian interpretation has been advanced to 

 account for all of them. 



The hypothesis of de Vries while ingenious does violence to many of 

 our most cherished conceptions of the general nature of hereditary 

 phenomena. De Vries assumes that pangens exist in three forms; 

 active, labile, and inactive. Two pangens are concerned in the above 

 series of forms, the rubrinervis pangen for strengthening of the vascular 

 bundles and the nanella pangen for stature. These pangens exist in 

 lamarckiana in the labile condition in which they occasionally change 

 to the inactive condition and thus produce the corresponding muta- 

 tions rubrinervis and nanella. Labile pangen X inactive pangen then 

 gives according to de Vries in FI the ascendency of either one or the 

 other condition to the complete exclusion of the other form in later 

 generations. Accordingly lamarckiana X nanella gives in FI lamarck- 

 iana and nanella which breed true in further generations. Similarly 



