No. 572] SHORTER ARTICLES AND DISCUSSION 499 



publishing on the first there could have been no objections to his 

 main contention that 0. biennis from the sand dunes of Holland 

 is capable of giving rise to true mutants. 



Stomps is continuing his studies on this same Dutch biennis 

 with the view of determining its possible powers of mutation, and 

 it is a pleasure to review his second paper 3 which presents some 

 extremely interesting data, a paper in which no important criti- 

 cism can be based on the source and character of the material em- 

 ployed. No wild species of evening primrose has been so long 

 under experimental and field observation or is better known to 

 the workers with Oenotheras than this plant. The species has 

 proved uniform in culture to a remarkable degree and it would 

 be difficult to find a type of (Enothera so free from suspicion of 

 gametic purity. The species appears to have been in Holland 

 since pre-Linna-an days and is therefore very old. As material 

 for experimental studies on mutation the Dutch biennis seems to 

 the writer the best of all the Oenotheras so far brought into the 

 experimental garden. 



The starting point of Stomps "s cultures of (Enothera biennis 

 was a plant transplanted from the sand dunes in 1905. From 

 seed of this plant, self-pollinated, a second generation was grown 

 in 1910, three selfed plants of which gave the seed for a third 

 generation of 430 individuals, and a fourth generation of 490 

 plants was grown from two selfed plants of the third generation. 

 Thus in all 930 individuals were observed in the third and fourth 

 generations from the plant that gave rise to these pure lines. 

 It is true that these lines have not been under selection for many 

 generations, but. considering the stability of the species and its 

 habit of close pollination, it is very improbable that the source of 

 the cultures should have been a plant not representative of the 

 type. Furthermore, Stomps presumably will continue indefi- 

 nitely the lines now established and thus determine through 

 later generations whether their mutating habits remain constant. 



Among the 430 plants of the third generation there appeared 

 1 biennis nanella, 1 biennis semi-gigas and 1 individual of biennis 

 sulfurea; the first two came from the same mother plant. Among 

 the 490 plants of the fourth generation appeared 3 individuals of 

 biennis sulfurea, all from the same selfed mother. The variety 

 sulfurea differs from the species biennis in having flowers of a 



