Cellular Growth 103 



The processes of meiosis and gametophytic devclojiiiicnt are 

 changed by colchicine.-' ''• -•'• "''• ^^^- ^-^' ^--- ^^'' Resjionse depcntls iijion 

 the concentration, stage of tievelopment when colchicine reaches the 

 cell, length of exposme, and, of comse, concentration. As might be 

 expected, the spindle is inhibited, but there are also other changes 

 that accompany the colchicinc-elfect.^ For that reason the problem of 

 a "colchicine-meiosis" '" is included in this chaj^ter along with the 

 action upon embryo sac tievelopment^'* and pollen tube studies.^"' 



Colchicine acts upon cells dining their differentiation processes. 

 One noticeable change is foimd in the cell walls. •''^ Their chemical 

 composition is altered also, and various physical marks show that 

 action of colchicine is not limited to the mi totic s|)indle or upon 

 certain cytoplasmic constituents. "•''* Enough data are at hand to prove 

 that differentiation processes in plants are modified by colchicine. "'•'• 



53, 1.56, 151 



Among unicellular organisms, processes of division, enlargement, 

 and differentiation, are closely integrated within one cell. For that 

 reason one woidd expect to find the results from a colchicine exposure 

 difficult to interpret. Conceivably, all three processes go on within 

 one cell at the same time; hence, colchicine may act upon each phase 

 in a specific manner, yet simultaneously. If this interpretation is cor- 

 rect, the confusing picture drawn from the literature dealing with 

 colchicine and microbiological materials may be jjartly explained by 

 the inability to distinguish the specific process being studied, whether 

 a cell division, cell enlargement, or differentiation and matmation. 

 There is general agreement that the actions reported in this research 

 are contradictory. Under some conditions, however, colchicine is 

 effective if introduced to specific microbiological cultures within 

 certain concentrations. 



A mechanism for action of colchicine upon jirocesses of gro;\th 

 and differentiation is difficult to visualize. Nevertheless, there should 

 be some aspects of metabolism that might help toward the solution 

 of this problem.if«- 1""'' ^'■'- "- i^s, 142. 180. 90! 5.;, w, 47, 4,s, 45 Generally, the 

 work with physiology^"^- ^^ has been done with such isolated pro- 

 cesses as enzyme reactions'-" or respiration^if* imder a restricted set 

 of conditions for experimental material. At least a start has been 

 made in this direction, but more can be done in the future. 



4.1: Colchicine Tumors in Roots, Hypocotyl, and Stems 



1 he root tumor forms at the region of elongation, a section be- 

 tween the meristematic area and the differentiated cells of a root^"- 

 35,79,82,02 (Fig. 2.1). Normally cells elongate linearly to the axis of 

 the root. They seem to show a polarity in this respect. When colchi- 

 cine is present, an enlargement of the cell takes place in all directions. 

 That is, an isodiametric expansion occurs, rather than a polarwise 



