520 Cannon : Studies in Plant Hybrids : 



have observed also that the peas used in the present study were 

 fertile ; they produced pods which were usually well filled with 

 seeds capable of germination. These observations are in harmony 

 with the manner of the formation of the spores ; no irregularities 

 whatever, which in any way were traceable to the plants as hybrid 

 organisms, were seen. If these observations are correct, the con- 

 elusion can hardly be avoided that the variations and reversions of 

 hybrid peas are associated with normal processes, such as are found 

 in the pure types, and hence that abnormalities are merely indica- 

 tions of the hybrid nature of the forms that bear them, although 

 by no means diagnostic characters. It is then a question fairly 

 open for the cytologist to determine, what the nature of those 

 processes are, and this has yet to be done. 



The hybrids used in this study, * Fillbasket x Debarbieux and 

 Express x Serpette, showed variation after the law of Mendel, 

 although I should state that they were not examined more than was 

 necessary to surely establish this point. The seeds from which 

 the plants studied were derived were from those of the first gen- 

 eration. The Fillbasket x Debarbieux seeds were yellow and 

 green, nearly in the ratio 3:1. Of course most of the flower-buds 

 were removed for study, but in a few cases I left the flowers to 

 fertilize themselves. The plants which came from the green seeds 

 bore green seeds only, and those from the yellow seeds bore seeds 

 that were both yellow and green in the ratio 3:1. In the crosses 

 in which Serpette was used as one of the parents, as for example 

 Express x Serpette, the Serpette dwarf character was noticed in 

 the offspring as presumably the recessive one ; it appeared in at 

 least one third to one half the total number of third-generation 

 plants. In Express x Serpette there were seventy-two plants 

 which resembled the Express ancestor, and thirty which were 

 dwarfed and which were like the Serpette race. The illustrations 

 (/. 34-37) show fairly well the appearance of these reversionary 

 types and the pure forms also. 



* I am indebted to Professor William Bateson for the seed from which the hybrids 

 were raised. Professor Bateson very generously sent me some first crosses, several of 

 the second generation and also the pure types. 



I wish also to acknowledge the assistance of Mr. Homer D. House, of Colum- 

 bia University, for aid in preparing material for study, and that of Miss Palmyre de C. 

 Clarke, of the New York Botanical Garden, who prepared the bibliography. 



