7 2 



PHARMACEUTICAL BOTANY 



g i 



FIG. 34. Semi-diagrammatic representation of nuclear and cell-division, a, 

 resting cell ready to begin division; b, the nuclear reticulum is assuming the form 

 ot a thickened thread, and the cytoplasm at opposite poles is becoming thread- 

 like to form the spindle fibers; c, the nuclear thread has divided longitudinally 

 through the middle, and the spindle fibers have become more definite; d, the nu- 

 clear membrane and the nucleolus have disappeared, and the nuclear thread has 

 become segmented into chromosomes which are assembling at the equator 01 the 

 cell. All of the phases of division thus far are called prophases. e, the metaphase, 

 where the longitudinal halves of the chromosomes are being drawn apart pre- 

 paratory to their journey toward the opposite poles; /, the anaphase, or move- 

 ment of the chromosomes toward the poles, is about completed, connecting 

 fibers extend from pole to pole; g, telophase where the chromosomes have begun 

 to spin out in the form of a nuclear reticulum. The connecting fibers have begun 

 to thicken in the equatorial plane; h, the connecting fibers have spread out and 

 come into contact with the wall of the mother cell in the equatorial plane, and 

 the thickening of the fibers throughout this plane has made a complete cell plate 

 within which the dividing wall will be produced; i, a nuclear membrane has been 

 formed about each daughter nucleus, and the dividing cell- wall is completed. 

 The two daughter cells are now ready to grow to the size of the parent cell in a, 

 when the daughter nuclei will appear as does the nucleus there. All highly mag- 

 nified. (Stevens.) 



