248 The Pedigree Families. 



family we have just considered, as well as two other 

 primary families which will be described in section 5 ; 

 not to mention a number of subsidiary families and cul- 

 tures. The main conclusion is that the facts of muta- 

 bility can be described by laws just as definite as the laws 

 of variability. 



The following generalizations apply in the first in- 

 stance to the new forms which have arisen from Oeno- 

 thera Lamarckiana; but it should be stated that they are 

 completely in accordance w^ith a whole host of observa- 

 tions, for the most part of a horticultural nature, on 

 other genera and families. 



I. N'ezu elementary species arise suddenly, without 

 transitional forms. A great point in my experiments 

 has been that the ancestors of the newly arisen forms 

 have always been accurately known, and often for many 

 generations back; and that they were either isolated as 

 a group (1887-1891) or that they flowered in isolating- 

 bags and were artificially fertilized (1894-1899). There 

 is no mention of any such precaution in horticultural 

 records. This precaution enables us to be certain that 

 each new form arose from the seed of a normal specimen 

 of Oenothera Lamarckiana. The new form always arises 

 with all the characters proper to it. Once the identity 

 of a seedling is recognized the characters which it will 

 gradually assume can be predicted, and in every case the 

 prediction has been fulfilled. 



Many opportunities for testing the degree of cer- 

 tainty in identifying seedlings offered themselves during 

 the course of the experiments, and especially when the 

 chosen seedlings were planted out and flowered in my 

 garden. 



When there are hundreds of individuals to record, 



