76 Colchicine 



for these experiments.^^ Normal metaphasic patterns are ^vell known 

 for this species at 25°C. Thus it was possible to judge the exact time 

 when a fully formed metaphasic spindle could be expected. Accord- 

 ingly, at this stage, the sj)indle fibers shone brighth- and chromosomes 

 Avere less brilliant against the light background of spindle fibers when 

 viewed through this polarization microscope. 



An egg cell in metaphase immersed in colchicine-sea water, showed 



1x10-5 3 5 IxlO-'* 3 5 1x10-3 3 5 1x10-2 



MOLAR CONCENTRATION OF COLCHICINE 



Fig. 3.4 — The average time for disappearance of metaphasic spindle of Chaetopterus 

 egg, disappearance measured by polarized light pattern. The stronger the concentration, 

 the shorter the time for complete disappearance of spindle. Temperature of sea water 

 25°C. (Adapted from Inoue, Experimental Cell Research Suppl. 2:305-18. 1952) 



a Steady disappearance of the spindle. This meant that colchicine was 

 destroying an already formed metaphasic spindle. 7 he rate for a dis- 

 appearance was directly correlated with concentration. In line with 

 jjre\ious data, then, the greater the concentration, the more rajiid the 

 destruction of the spindle. Figure .S.4 shows these relationships 

 clearly. For example, in one test, the disappearance of spindle occur- 

 red in 30 minutes with the concentration 5 X 10'^ M. But an increas- 

 ing concentration (5 X It)-^ M) reduced the same stage of a spindle 

 within 3 minutes. Moreover, these observations were made by con- 

 tinuous records from living cells and not fixed structures.^" 



By an entirely new technique the destructive action of colchicine 

 was traced from a fully formed metaphase spindle to the complete 

 disappearance. Finally, the cjuantitative relation I)et^veen concentra- 

 tion and disappearance supports the proposition that specificity has a 

 quantitative basis. 



