178 



INTRODUCTION TO CYTOLOGY 



IV 



FIG. 59. Mitosis in the spermatocyte of Salamandra. 



I, prophase, centrosomes in astrosphere substance; latter spread out on nucleus. //, 

 prophase; bivalent chromosomes formed; centrosomes beginning to diverge; central spin- 

 dle and asters developed. ///, late prophase: nuclear membrane dissolved; spindle 

 fibers attaching to chromosomes, centrosomes moving apart. IV, anaphase: connecting 

 fibers prominent. V, telophase: constriction of cell nearly complete; mid-body forming 

 on central spindle or interzonal fibers. (After Meves, 1907.) 





1 



FIG. 60. Elaborate achromatic figure in oocyte of Pisciola. X 1000. 

 (After Jfiroensen, 1913.) 



