HISTOLOGY 



the astral fibrils. These latter are very long and stretch out into the 

 cytoplasm almost to the cell- wall in some places. The chromosomes are 



mossy at this time 

 and the nucleolus 

 sometimes persists as 

 it has done in our 

 example. 

 Figure 41 



shows 

 the figure completed 

 and ready for the 

 division of the chro- 

 matin. The spindle 

 fibrils are at their 

 best development, 

 and some of them 

 can plainly be seen 

 to have become at- 

 tached to opposite 

 sides of the chromo- 

 somes and be pull- 

 ing them apart. The 



FIG. 41. Same process at time of formation of equatorial 

 plate of chromosomes. 



chromosomes are shorter and smoother than they were in the preceding 



stage. They are bent or V-shaped rods which are first split at their 



apex. It can be seen 



in this figure that the 



strain on the spindle has 



caused a sinking in of 



the whole surface at the 



point where this strain 



is greatest. 



A peripheral layer of 

 the cell is left in its origi- 

 nal position. The next 

 figure (42) represents a 

 stage, subsequent to the 

 last, in which the chro- 

 mosomes have been 

 drawn apart. The form 

 is well shown. As in 

 the hyacinth figure, the 

 spindle fibrils are shown 



between the parting groups of chromosomes, while the fibrils which 

 are seen between the chromosome groups and the centrosomes 



FIG. 42. A cell of the same kind showing separation of 

 the chromosomes. 



