48 KARL B. KRISTOFFERSON 



the serration of the leaves and the pointed sepals (the oxyloha-charixc- 

 ters) are due to one single Mendelian factor O with a pleiotropic 

 effect in leaves and sepals. Its absence results in serrulated leaves and 

 rounded sepals of the paroiflora-type. 



Although already the f^-generation shows that a monohybrid 

 segregation took place I thought it advisable to verify this assumption 

 by raising the Fa-generation. The result is seen in table 2. All descen- 

 dants of Fo-phïnts of parviflora-iypc — totalling 19 lines with 1268 

 plants — bred true in Fg. 44 lines, descendants from Fa-plants of 

 oxyloba-iype, were obtained. 17 lines, with 1083 plants in all, bred 

 true, and 27 lines showed segregation in oxyloba- and parviflora-types. 

 The ratio of constant and segregating lines pro 3 is l,i59 : l,84i. The 

 theoretical ratio is 1 : 2rfc 0,2i32. The deviation (D) is 0,i59 and D/mu 

 = 0,75. Thus, the agreement is good. The ratio in the segregating 

 Fa-lines is 1097 plants of the oxyloba-iype and 340 of the parviflora- 

 type. The observed ratio pro 4 is 3,054 : 0,946. The theoretical ratio is 

 3 : 1 rb 0,0466. The deviation (D) is 0,054 and p/nik = l,i6. The devia- 

 tion is thus a little greater than allowed and, consequently, the agree- 

 ment between the observed and the theoretical values is not quite 

 satisfying. The cause of the deficient number of the parvi flora-types 

 probably depends on the greater vitality of this type, curiously enough, 

 as will be shown in the following. 



Both species show an excellent vitality. M. parviflora seems, 

 however, to be a little more vigorously developed in the vegetative 

 parts; the main-axis, in particular, seems to be somewhat higher and 

 thicker. The weight of the fruits of the former is also greater; it 

 amounts to 4,70 gr. in M. parviflora and 3,95 in M. oxyloba pro 100 

 fruits. I have further the impression that the seeds of M. parviflora 

 germinated somewhat more rapidly. The above mentioned differences 

 seem to be applicable both to the pure lines and to the oxyloba- and the 

 parviflora-iype^ obtained in F,. It may be the more rapid germination 

 of the parvi flora-type that has caused the deficit of this type. When 

 sown in pots most seeds remain without germinating for at least a 

 month, and then they grow up very irregularly. In order to accelerate 

 the germination the seeds of some lines (Fa) were scratched with sand- 

 paper and then brought to germinate in filter paper. These seeds ger- 

 minated very well. The seeds of the Fs-generations were put in the 

 paper whithout being scratched. As only a few seeds germinated a cut 

 witli a knife was made in the seed coat of the remaining seeds; they 

 germinated then within 8 — 10 hours. The seedlings of the seeds already 



