Mechanism of Colchicine-Mitosis 



421 



or pro-metaphase, is by no means limited to colchicine or even to 

 chemical agents. From some angles, it appears as an entirely non- 

 specific reaction of metaphase to agents as different as cold, nitrogen, 

 hydrostatic pressure, lipid-solublc hydrocarbons, or heavy metals. 

 However, that it is in most cases more than a "narcotized" mitosis 

 is evident from the data about sulfhydryl groups, colchicine deriva- 



TABLE 17.5 



Percentage of Mitoses After Colchicine and 

 Adenosine-triphosphoric Acid (ATP) in 

 Cultures of Fibroblasts 

 (After Lettre and Albrechti^*) 



tives, and synergic activities. It is also evident at this point that fur- 

 ther progress will only be possible when the biochemical and physio- 

 logical properties of the spindle are better known. Mitotic poisons 

 are useful tools for this purpose, and it may well be that the solution 

 of this problem will lead rapidly to an understanding of the {proper- 

 ties of colchicine. The difficulties of this task are great, and resemble 

 in many aspects those of the study of muscle contraction. The spindle 

 structure is however relatively simple, as far as can be known at this 

 time, and its contractility and reversion to a nonfibrous "hyaline 

 globule" are problems of which a solution appears possible in the 

 not-too-distant future. 



Colchicine, from all that has been said in this chapter, must be 

 considered a singular substance. Not only does it possess remarkable 

 side-effects, such as its action on gour, the colchicine-leukocytosis, its 

 action on the nervous system and on muscular contraction, its induc- 

 tion of specific malformations in embryos; it is also the most efficient 

 and active of all mitotic poisons known — with the exception of de- 

 rivatives of the colchicamide series. It is also the mitotic poison to 

 which the largest amount of work has been devoted. While some 

 substances like podophyllotoxin have received great attention, others, 

 such as the arsenical derivatives, have hardly been studied from the 

 angle of mitosis. It is not because colchicine was one of the first- 

 discovered spindle poisons that it received such attention. Chloral 



