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 (Belajeif, 24 Stras- 

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

 the first mitosis originates as a multipolar structure, which 



A 



D 



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

 Hemerocallis fuh-a, with live and eight microspores in process of formation, 

 A x 1000; B x 6:25; after Jlel. 33 C, Euphorbia corollata, with live microspores 

 of equal Bize within mother-cell; x 6-25; after Lyon. 40 D, Begonia sp., with three 

 microsporia from a mother-cell: x 400. E, Ficaria ranvtteuToides, with six micro- 

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

 division of one of the spores of the tetrad, x 400. D-E, after Wille.» 5 



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



