778 



Colchicine 



early in the twentieth century and the next significant colchicine ex- 

 jjeriments.®^ Colchicine has been tried recently for a number of 

 mosses, using protonemata and propagula, treating the tissues in 

 special culturing media. Size differences between colchicine-treated 

 and untreated cells have been used as criteria for the changes in num- 

 ber of chromosomes (Table 4.4) . 



Diploid gametophytes of the male and female thalli from Mar- 

 chantia polymorpha were made by colchicine.^ Chromosomal check 

 showed that the numbers were increased. Another hepatic, Palla- 

 xiacinia spp., was subjected to colchicine. i"^' Again new patterns of 

 eroAvth showed that chanoes were induced. One mav assume that the 

 number of chromosomes was increased, although the modification in 

 cellular form without a corresponding increase in chromosomes makes 



Fig. 4.6— Embryo-sac stages of Tradescontio. Untreated stage with cells distributed In 



the sac and a smaller cavity. Treated stage with all nuclear material grouped in the 



center of sac. The size is not a response to polyploidy. (After Walker) 



