CHAPTER 4 



Cellular Growth. 



The senior author observed unusual "spearlike" tips torniing on 

 AJliurn roots immersed in a 0.01 per cent solution of colchicine. After 

 24 hours startling changes in the roots were noted^^ ^^f. Chapter 2) . 

 Colchicine-titmor,^^ the name given to this growth, is appropriately 

 descriptive. Similar anomalies were observed earlier by Nemec and 

 others.35 xhis growth pattern can also be reproduced with chemicals 

 other than colchicine or by certain physical treatments.'^^- ^-^ Although 

 the c-tumors were not new to biology, the revival of interest in colchi- 

 cine brought them to the attention of many experimenters.^*- ^^- ^^' ^^• 



44, 37, 59, 55!^13?., 115, 111, OU, SS, 02, 154, 128. IS, 4, 10. S. 21 



Roots with c-tumors may have some cells with many chromosomes 

 within the single cells, l)ecause polyploidy is a consequence of c- 

 mitosis. The correlation between larger leaves, stems, seeds, and 

 Howers, and increasing numbers of chromosomes is well established. 

 135, 152 yi^is concept influenced the first conclusion that c-tumors 

 were directly correlated with the polyploid cells. On the contrary, an 

 enlargement of root tijjs is not the result of polyploid cells induced 

 by the drug, even though polyploid cells may be created at the same 

 tmie the c-tumor is formed.^^ -fhe c-mitosis and c-tumor are inde- 

 pendent processes. *- 



Now we know that in similar manner, enlarged cells may be in- 

 duced in Aarious parts of plants.^"'' All these anomalous formations 

 induced by colchicine are the result of changing the growth pattern. 

 •5-' 90 Such structures as pollen tubes,'-''' •"'"• i" stylar cells of the flower, 

 1*^ hair cells of stem and root,-'-^- 55- 1^-^ hypocotyl, and other somatic 

 cells all show particular enlargements after treatment with colchicine. 

 They are in contrast to the untreated or normal cells that enlarge by 

 a cell tension that shows distinct polarity. By a broad interpretation, 

 all deviations expressed as growth patterns and appearing as a re- 

 sponse to colchicine will be classified as c-tumors, in spite of the fact 

 that this name originally designated a specific kind of root tip en- 

 largement after treatment with colchicine. 



[102] 



