CONIFERALES 305 



an appalling literature has accumulated; less is known about the re- 

 duction in megasporogenesis, because it is tedious to get the desired 

 stages. In the gymnosperms not much is known, even about the re- 

 duction in microsporogenesis, and still less is known about reduction 

 in megasporogenesis. Reduction certainly takes place, usually giving 

 rise to a row of four megaspores, the lower one of which functions, 

 while the other three abort (fig. 310). After the first reduction divi- 

 sion, it often happens that only the lower cell divides, giving rise to 

 two megaspores, only the lower one of which functions. The upper 

 cell of the row of three is not a megaspore, because it still has the spo- 

 rophyte number of chromosomes. So many cases of a row of three are 

 reported that it would seem as if there might be a tendency toward 

 the eHmination of the division of the upper of the first two cells. 

 With the reduction division, the sporophyte generation comes to a 

 close. The megaspore is the first cell of the gametophyte generation. 



