TETRAPLOIDS 



117 



tomato has 144 chromosomes (haploid 72 chromosomes). 

 These chromosomes are shown in Figs. 70 and 71. 



Giant haploid Giant diploid 



12 144 



C d 



Fig. 71. 



a, Haploid ; &, diploid cell and chromosomes of tomato ; c, haploid, 

 and d, diploid cell and chromosomes of tetraploid tomato. (After 

 Winkler.) 



As has been said, there is no obvious relation in these 

 cases, as far as known, between grafting and the forma- 

 tion of tetraploid cells in the callus. How these cells arise 

 is uncertain. It is possible that two cells of the callus fuse 



