PHANEROGAMIA 



513 



The Development of the Sexual Generation in the Angiosperms ("). On 

 germination the MICUOSPORES of Angiosperms form an antheridial mother-cell 



(Fig. 497 m) which is clearly de- 

 limited from the large pollen- 

 tube cell, but is not enclosed 

 by a cell wall. The antheridial 

 cell passes into the pollen-tube, 

 and sooner or later divides into 

 two generative cells (Fig. 497 g). 

 The nucleus of the pollen-tube 

 (k) is usually visible in the 

 neighbourhood of the gener- 

 ative cells. The absence of the 

 small prothallial cells, and of 

 a sterile sister-cell of the au- 

 theridium, as well as the 

 absence of a cell wall from the 

 mother-cell of the autheridium, 

 are points in which the Angio- 

 sperms differ from Gymno- 

 sperms. The reduction of the 

 male prothallium has thus gone 

 so far that only the indispens- 

 ably necessary parts remain. 



The characteristic differ- 

 ences which the Angiosperms 

 show from the general course 

 of development of the MACRO- 

 FIG. 495. Cyrnose inflorescence (dichasium) of Cerastium SPORANGIUM in the Phan- 

 colllniiin. t-t"", successive axes. (After DCCHARTRE.) erogams commence with the 



Fit;. Ut>. Scorpioid cyme of Symphytum 

 aspfrrimum. (After DUCHARTRE.) 



FIG. 49". Pollen-grain of Lilium Martagon and its 

 germination, k, Nucleus of the large vegetative 

 cell of the pollen-tube ; m, small mother-cell of 

 the antheridium ; g, generative rolls. (After 

 GUIONAHD. x 375.) 



2 L 



