50 Colchicine 



It was found that the arrested mitoses lasted from 5 hrs. 26 min. to 

 14 hrs. 20 mill., and later were destroyed. 



The spleen of Siredon Avas crammed with arrested mitoses five 

 days after colchicine treatment. It the figures given above are ac- 

 cepted, the correlation of the two sets of data— (1) duration of c- 

 mitoses and (2) the appearance of large numbers five days after 

 treatment — naturally raises some questions that appear important. 

 In Xe}ioj)us. while cellular degeneration may be rapid, the percent- 

 age of metaphases remains very high as long as three days after colchi- 

 cine. In Siredon,, it is possible that in the spleen only the intact cells 

 remain visible, the others being washed away by the blood stream, 

 so the results are not as contradictory as they seem at a first glance. 



It is thus most probable, from what is known about the pharma- 

 cology of colchicine (cf. Chapter 7) , that in warm-blooded animals, 

 and "particularly in mammals, arrested metaphases are destroyed in 

 less than ten hours. This is in agreement with the histological evi- 

 dence of nuclear degeneration,--'- "i and must be kept in mind when 

 colchicine is used as a tool for the study of growth. 



2.5: Processes Leading to Interphase 



Chromosomal formation is not stopped by colchicine. Under cer- 

 tain conditions the process is slowed down or the delay is so pro- 

 nounced that there is an appearance of its formation being stopped. 

 For example, many prophase-metaphase types are essentially arrested 

 prophases. Also we pointed out how colchicine might stop chromo- 

 somal formation during prophase and turn the process back to inter- 

 phase.93' '^^ 



There are three ways in which chromosomes change to interphasic 

 dispersal under the influence of colchicine — exclusive of recovery, 

 which we will discuss in a subsequent section. They are: (1) the just- 

 mentioned prophase reversal to interphase;39- 03 (9) the changes 

 from any of the arrested metaphases,^' -• 34 i g., prophase-metaphase, 

 ball metaphase, exploded metaphase, star and distorted star meta- 

 phases; and (3) a full c-rnitosis through c-anaphase and c-telophase 

 transformations.''''^- ^^' 



Basically, the physical change that takes place in the chromosome 

 does not differ much in either of the three routes taken. Therefore 

 a general description of this process shall include the changes- 

 common to plants and animals. Moreover, the process is not very 

 different from a regular telophasic transformation found in a normal 

 nuclear mitosis.-'-^ In all probability the unraveling, loss of chromatic- 

 ity, and general physical changes are very similar." Colchicine does 

 not prevent the return of chromosomes to interphase and similarly 



