Spindle and Cytoplasm 83 



chicine beains. Tlie stars ^verc the "arrivals" in this case. While 

 Triturus cells developed, the star showed that the effect of colchicine 

 Avas "departing." 



\Xe may conclude that the star i'ornis when centriole, centromere, 

 and chromosomal fibers interact while continuous fibers are sup- 

 pressed. A mitotic polar metaphase appears much the same as the 

 star, btit the latter has very small, if any, stainable achromatic core. 

 The size differences have been demonstrated in several instances. '^^' ^' ^^ 



Chromosomes occasionally fall outside the star cluster. Lagging 

 chromosomes may be observed in tmtreated cells. Neuroblasts, treated 

 with very weak solutions of colchicine, consistently show lagging 

 chromosomes. The lost chromosome is confirmation that a partial 

 spindle inactivation takes place when these partictdar types form.''-* 



Mtdtiple stars (Fig. 3.2/) are basically the same as the single star, 

 except for several focal centers instead of one. If two or more chromo- 

 somes fell outside the first star, a second could form. This type is most 

 common when cells are recovering in AUiuin root tips. Increasing the 

 ninuber of chromosomes shows a corresponding increase in the 

 number of multiple stars. Multiplex stars have been demonstrated in 

 both plants and animals, during recovery as well as during active 

 treatment. Triturus showed the bimetaphase and trimetaphase, c(|ui\ a- 

 lent to nudtipolars, five to six days after recovery. '^^ 



Distorted stars- are not proved as easily as the star formation. Two 

 explanations ha\e been given. One, the action is a response of centro- 

 meres and a centrosomic center, but the staining procedures did not 

 bear otit these assumjjtions. l\vo, the hxaline globule which forms 

 when sjiindle fibers disajipear. becomes ^vedged between the chromo- 

 somes, distorting the star.-^' Either explanation may be considered \ alid 

 tmtil more information is at hand. 



Unoriented metaphases. such as ball, clumped, prophase-meta- 

 phase, or exploded types, do not show activity on the chromosomes or 

 any j^art thereof. The term uiioriruted is entirely appropriate- for 

 such figures (Fig. 3.IG, 3.2rf) . 



An exjjloded or scattered arrangement has been observed in many 

 plants and animals (cf. Chapter 2) . It the disappearance of a meta- 

 phasic spindle is follow^ed by the birefringence pattern,^' one may 

 assume some mechanical explanation for the exploded tyj)c. for as 

 soon as the spindle disappears completelv, the chromosomes seem 

 to scatter as if they were held on the ecjuatorial jjlate to the very last 

 moment. Disappearance of the continuous fibers did not permit the 

 scattering. Not tmtil chromosomal fibers disap]:)eared did the chromo- 

 somes disperse. This confirms that the exploded metaphase originates 

 when both chromosomal and contintious fibers are destroyed. Such 

 observations support the concepts that a fidl c-mitosis may in\f)lve an 



