INFERENCE OF ORIGIN 



195 



Solanum nigrum 

 5. Ly coper sicum 

 Canna aureo-vittata 

 Campanula persicifolia 

 Lathyrus odoratus 



Funaria hygrometrica . 



) j0rgensen, 1928 ; cf. Upcott, 



) 1935- 

 Honing, 1928. 



Gairdner and D., 1931. 

 Faberge, 1935 ; Upcott, 



unpub. 

 V. Wettstein, 1924. 



These are all autotetraploids except the structurally heterozygous 

 (Enothera, which may be considered as an autopolyploid for this 





Q 



"f®® ogo 



000 O 





r^^ r\ 



\)) I 





Fig. 67. 



Fig. 68. 



Figs. 67 and 68. — Pollen grains of Solanum. Fig. 67. — S. nigrum : 



a, X (haploid) ; h, ix ; c, ^x ; d, ^x. Fig. 68. — a, S. nigrum {2x). 



b, S. luteum. c, the diploid hybrid, d, the tetraploid hybrid. 

 X 160 (from Jorgensen, 1928). 



purpose, since, as has been seen, the differences between its 

 homologues are so arranged as not to interfere with pairing. In 

 Funaria, v. Wettstein found that auto-octoploids produced 

 artificially without hybridisation were sterile. When octoploids 

 were similarly raised from hybrids between different species and 

 genera they were fertile, the diploid l^brids being sterile except 

 in the production of unreduced gametes (cf. Burgeff, 1930 ; Haupt, 

 1932 ; Schweizer, 1932 ; Allen, 1935). 



Further, diploid hybrids of intermediate fertility give tetraploids 

 of intermediate fertility and with an intermediate frequency of 

 quadrivalents, e.g., in Vicia (Schweschnikova, 1929 h), Crepis 



