44 



INTRODUCTION TO EMBRYOLOGY OF ANGIOSPERMS 



Fig. 33. Cytokinesis in microspore mother cells of Melilotus alba. A, telophase 

 of Meiosis I. B, metaphase of Meiosis II. C, end of Meiosis II, showing three 

 of the four microspore nuclei. Note large extranuclear "centrosome-like bodies" 

 seen here and in A. D, microspore nuclei in resting stage. Spindles have almost 

 disappeared and protoplast has begun to invaginate at the periphery, at points 

 equidistant from the nuclei. Note origin of special wall, shown in black. E,F, 

 formation cf vacuoles in portions of cytoplasm lying between nuclei. G, special 

 wall entering furrows. //, special walls have met in center, forming partitions be- 

 tween microspore nuclei. I, fully formed microspores. (After Castetter, 1925.) 



