lis 



THE AMERICAN NATURALIST [Vol. XL VII 



Stomps lays emphasis on the purity of his material of biennis 

 and cruciata which had been carried along for several years in 

 pure lines from original wild plants of the sand dunes. He 

 states that the crossing of these two forms is concerned alone 

 with the floral peculiarities of cruciata, since in all other char- 

 acters the two types are the same. It seems to the writer hardly 

 possible that lines so well established as biennis and cruciata 

 can be absolutely the same in all respects except that of flower 

 form, although this is obviously the most important point of dif- 

 ference. The American forms of crucial a are exhibiting among 

 themselves remarkable differences of germinal constitution. 



The observations of Stomps are of interest, He obtained in 

 the second generations from crosses between bi< nnis and cruci- 

 ata two marked variants. These are called biennis nanella and 

 biennis scmi-gigas because of the similarity to somewhat cor- 

 responding variants from Lamarckiana. We are not informed 

 as to the proportions in which these new forms arose, a point of 

 importance since w r e should like to know whether they are very 

 rare, as say 1 : 10,000, or more common. 



The first variant, biennis nanella, appeared in the second gen- 

 eration of the cross biennis X cruciata. This cross gave an F t 

 hybrid with heart-shaped petals as in the mother plant; no 

 statements are made as to the size relations. In the F 2 genera- 

 tion there was a splitting into forms of biennis and cruciata; 

 we are told nothing of the proportions of these individuals in 

 the cultures or of their range of variation. One of the biennis- 

 like forms presented a dwarf habit which distinguished it from 

 the biennis parent in much the same way that nanella is dis- 

 tinguished from Lamarckiana. This plant, biennis nanella, 

 differed from Lamarckiana nanella by the same characters that 

 distinguish biennis from Lamarckiana, An important point of 

 resemblance to Lamarckiana nanella lay in its sensitiveness to 

 bacteria which Zeylstra discovered within the tissues of this 

 type and showed to be responsible for certain abnormal char- 

 acters. De Vries has shown that Lamarckiana nanella grown in 

 a soil treated with calcium phosphate became healthy and Stomps 

 found that his biennis nanella responded in a similar way to this 

 treatment. 



The second variant, biennis semi-gigas, appeared in a second 

 generation from the reciprocal cross cruciata X biennis. This 

 cross also gave an F x hybrid with flowers of the biennis type 



