THE MALE GAMETOPHYTE 



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 



A 



C 



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

 Ilemerocallis 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 

 microspores from a mother-cell ; x 400. B, Ficaria rannnculoides, with six micro- 

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

 division of one of the spores of the tetrad, x 400. B-B, after Wille.i 6 



gradually becomes bipolar (Figs. 61, 61a). 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. 



