476 Colchicine 



and the sulfonamides. Some work in this direction has been carried 

 along and ^\'\\\ he sunmiarized now. 



17.5: Synergists and Antagonists 



A possible synergism between animal gro^\■th hormones and col- 

 chicine has been considered in Chapter 9. In plants, some changes 

 visible alter colchicine have been interpreted as evidence'^- -'^^ ^*^'- '^' 

 79. 87 of hormonal action of the alkaloid. This has not been jnoved 

 (cf. Chapter 4) . In animal and i)lant cells, the antagonism of 

 7neso-'mos\to\ and colchicine is still a subject under discussion which 

 merits to be reviewed here. Mention will also be made of a long series 

 of experiments on fibroblasts in tissue cultures. These have led to a 

 novel theory about c-mitosis which ^vill l)e pioperly considered in 

 the light of all the facts already gathered in this chapter. 



77.5-/.- Meso-inositol. y-HexacJilorocyclohexant' ("Gammexane") , 

 a widely used insecticide, has been reported by several authors to 

 induce c-mitosis in Allium and other plant cells.--' ■^•'^•■''-'' Both the y 

 and the b isomers ha\'e been found to be active, i"' while the first only 

 is of use as an insecticide. Polyploidy and chromosome fragmentation 

 have also been recorded. Gammexane is probably an antagonist of a 

 naturally occurring substance. meso-inositoL having the same stereo- 

 isomeric structure as this sugar, the biological significance of which 

 appears from its presence in many types of cells. 



It was thus not surjjrising that in 1948 it was announced that 

 ?/K'50-inositol, (but neither d-inositol nor D-sorbitol) prevented, in 

 proper concentrations, the c-mitotic activity of Gannnexane in Allium 

 cepaJ*' It was, howe\er. more surprising and most interesting that 

 7neso-inosito\ was claimed to jjrevent also the sjjindle effect of col- 

 chicine. The results were gi\en as j^ercentages ol the different stages 

 of mitosis, and it is to be regretted that no counts of the total num- 

 ber of cell di\isions were recorded. Inositol alone did not interfere 

 with mitosis. The formation of c-tumors, both by Gammexane and 

 colchicine, was also prevented. ''' 1 hese results were checked over a 

 wider range of concentrations and times by another author, who lonnd 

 that meso-inosho\ merely delayed the c-mitotic eftect of colchicine, 

 which was visible, as in the controls, after 24 hours.-- Similar delays 

 were observed with other sugars, a solution of saccharose (0.95 mg/ml) 

 suppressing all colchicine mitoses in root tijjs observed after tour 

 hours of treatment, while after 24 hours the c-mitotic effect was 

 normal.-- Modified cell permeability was thought to explain the re- 

 sults obtained with //(07>-inositol. A confirmation of these findings 

 was found in the observation that colchicine and jjodophyllotoxine 

 effects were antagonized in the egg of the sea urchin Lyt echinus varie- 

 gatus by glucose.-" The antagonism was never total; it was suggested 



