730 



Colchicine 



Fig. 4.9 — The network of Hydrodictyon becomes distended and unorganized by treat- 

 ment with colchicine. A. Control cells. B. Treated cellular network. (After Gorter) 



Sugar beets developed alter a treatment showed consistent size 

 increase for roots, but polyploidy was not found with these particular 

 cases. Larger roots are regularly developed in known triploid and 

 tetraploid progenies."-' Barring some error in method, the explanation 

 for larger beets falls outside the scope of polyploidy. Perplexing 

 variations appeared in subsequent progenies of sorghum plants that 

 were treated with colchicine.^*' Chromosomal numbers were diploid, 

 so polyploidy was not correlated Avith these types. Additional proge- 

 nies from treated F^ plants were significantly lacking in uniformity 

 as compared with untreated cases. ^"^ These variants were not classified 

 with aberrants reported previously and described above, i.e., the 

 Lio-ustyiun variations, because while the lack of uniformity followed 

 a segregation pattern, the control material did not show a smiilar 

 segregation.''- Although no explanation was given, the hereditary 

 mechanism was not ruled out as a possible cause. The instance is 

 cited in this discussion primarily to emphasize that results from treat- 

 ing colchicine are not in every case quickly disposed of as the effect 

 of a c-mitosis, leading to polyploidy which in turn is the explanation 

 for new variants. That colchiciire has caused a more basic deviation 

 not correlated with a doubling of chromosomes seems quite rea- 

 sonable even though the full explanation remains in question. 



