THE MALE OAMETOPHYTE 



129 



opinion as to whether a qualitative division occurs. At present 

 the weight of evidence is against such a division. 



According to nearly all recent observers (Belajeff, 24 Stras- 

 burger, 25 Mottier, 26 Lawson, 35 Miss Byxbee 52 ) the spindle in 

 the first mitosis originates as a multipolar structure, which 



FIG. 60. Microspore mother-cells producing more or less than four microspores. A-B, 

 Hemerocallis fulva, with five and eight microspores in process of formation ; 

 A x 1000; B x 625; after JuEL. 33 <?, Euphorbia corollata, with five microspores 

 of equal size within mother-cell ; x 625 ; after LYON. 40 D, Begonia sp., with three 

 niicrospores from a mother-cell ; x 400. E, Ficaria ranunculoides, with six micro- 

 spores, x 400. F, Azalea indica, with six microspores, three having come from the 

 division of one of the spores of the tetrad, x 400. D-E, after WILLED 



gradually becomes bipolar (Figs. 61, 61<z). In a few cases mul- 

 tipolar spindles have been described for the second mitosis. In 

 vegetative cells the spindle first appears as a pair of dome- 

 shaped prominences or caps. Transitions between the two 

 modes are not lacking. 



