MUTATIONS OF OENOTHERA SUAVEOLENS DESF. 243 



their origin must be the same as that of numerous dwarfish varieties 

 of garden plants. Any explanation must include all of them. The 

 sulfurea mutations are evidently due to the disappearance of one 

 of the factors of the bright yellow color of the evening primroses. 

 They appear at once, just as the numerous color varieties of our 

 garden plants have occurred in horticulture. It is of no use to give 

 a separate explanation for them. 



Some mutations, parallel as well as special ones, are of a taxo- 

 nomic nature, repeating characters which are specific in other genera. 

 I shall have to describe in this article an apetalous form of Oe. 

 suaveolens and this condition is a specific mark for Fuchsia pro- 

 cumbens, F. macrantha and in other instances. Its explanation should 

 be the same in both cases. 



This analogy between specific and varietal marks in nature as well 

 as in horticulture on one hand and some of the experimental mu- 

 tations on the other hand constitutes the link between the theory 

 and the experimental researches. The common aim of all critics 

 in this field is to prove that this analogy does not exist, and that 

 the phenomena observed in our experiments are essentially different 

 from the origin of species and varieties in nature. Therefore it is 

 desirable to broaden the experimental field and to study the mu- 

 tability in other species, as Stomps, Bartlett, Gates, Klebahn and 

 others have already done. 



It is from this point of view that I have studied the mutability 

 of Oe. suaveolens Desf. This form, which is manifestly different 

 from Oe. grandiflora Ait., is widely distributed throughout France, 

 where it occurs most profusely in the western departments and in 

 the vicinity of Paris (Opera VI, p. 568). I received seeds from the 

 forest of Fontainebleau through the kindness of Prof. L. Blaringhem 

 in 1912 and started my race from one of these. In the following 

 year I visited the same spot in his company and assured myself 

 of the purity of the station. At other places in the same forest, Oe. 

 suaveolens grows together with Oe. biennis and the seeds from these 

 stations contained some hybrids. For my experiments I have only 

 used the plants grown from the pure station near Samois. Later, 

 in 1914, I sowed some seeds, collected by M. Eugene Simon in the 

 neighborhood of Royan, on the western coast of France near Bor- 

 deaux; they produced exactly the same form. The plants from the 

 seeds of Prof. Blaringhem proved to be a uniform lot. Two of them 

 were artificially self-fertilized in bags, and yielded two races, which 

 were kept separate in the lapse of the generations and constituted 



