706 



Colchicine 



ling that has already elongated, let us say to 23 mm. before treatment 

 begins, shows practically no swelling at the hypocotyl.^i'- All these 

 points fall in line with the proposition that tumor formation is 

 basically a growth response to colchicine (Fig. 4.1) . 



Stems of Tradescaniia cut from the plant and placed in colchicine 

 show extreme swelling at the node where leaves are attached.i^^ The 

 nodal enlargements are in every respect comparable to root and hypo- 

 cotyl tumors. A petiolar swelling also may occur if expanding leaves 

 are placed in colchicine. 



The growth responses observed for roots and stems raised the ques- 

 tion of a possible hormone action. However, the standard tests for 

 measuring phytohormone potency gave negative results."'^- ^o- ^^ No 



CONTROL 



40x10-3 



10x10-3 



5x 10-3 

 2xlO-3 



1 



8 DAYS 



Fig. 4.1 — Elongation of hypocotyl of Lepidium seedlings. Reduction in length is pro- 

 portional to concentration of colchicine. (Adapted from Gremling) 



