7A Colchicine 



by regular uncoiling processes, similar lo the regular tcloj:)hasic trans- 

 formations. During later stages a "cytoplasmatization" of spindle or 

 ■lluidity" was created."- By this process the spindle was transformed. 



Metaphasic spindles were destroyed in pollen cells of Ephedra. 

 The concentration was a strong one (2 per cent) . and rexersion to 

 interphase was rapid. The total time for a cell to proceed through 

 a regular mitosis was no different from the time taken for a rever- 

 sion. A full c-mitosis would have taken a longer time. This rapid 

 conversion back to interphase led to the conclusion that colchicine 

 did not delay the mitotic cycle. Preliminary results unptdilished by 

 the authors show that concentration is a most important consider- 

 ation for Ephedra as well as other cells. Reversions can proceed very 

 rapidly under the action of colchicine.^' 



The data from Tradcscantia and neuroblasts confirm an opinion 

 stated earlier that the destructive action is cjuite as notable for col- 

 chicine as its inhibitive activity. The main difference lies with the 

 concentration. Stronger solutions arc recjuircd to destroy a fiber at 

 anaphase than to inhibit its formation during prophase. 1 hat is 

 why a broad range of concentrations is imperative to obtain a full 

 picture of c-mitosis. 



3.3-3: Arbacia j>un( tiilata. Colchicine applied to eggs of Arbacia 

 at a specific time after fertilization, showed a clisintegrating action upon 

 the astral ray.^'^ They faded out shortly after the drug entered the cell, 

 and a "lakelike" body appeared at one end of the mitotic figure (Fig. 

 3.3) . The chromosomes were massed in the center of the cell. If the 

 drug entered the cell when two polar regions had already developed, 

 then two lakelike bodies were seen, one at each end. Finally, a still 

 later stage showed the chrom()sf)mes in two anaphasic chmips and a 

 lake area encircled the entire figure. 



1 here is a critical time beyond which the colchicine does not stop 

 cleavage, but then a fluidity may be developed around each set of 

 chromosomes even though separate cells were formed. 



The disintegration of amphiasters was rapid, and restitution nuclei 

 were formed after a scattering of chromosomal portions was obtained. 

 The destruction of the mitotic sjMndle at metaphase blocked cleavage 

 effectively. Thus, the spindle components are vitally important to 

 cleavage. The independence of the spindle action and a rhythm of 

 viscosity changes of the cortical layers, independent of mitosis, have 

 been demonstrated. The two processes may go on simultaneously. 

 These have been shown by methods for obser\ing the changes at the 

 outer layer of the cytoplasm.-"' "- 



lliere can be no doubt that spindle fibers already formed can be 

 destroyed. The specificity between drug and fiber is necessary for such 

 action. A confirmation from materials representing diverse biological 



