THE FEMALE GAMETOPHYTE 



143 



lenchymatous cells, but the upper part continues to grow, sometimes 

 reaching a considerable distance into the style. Fertilization occurs 

 here by the incoming pollen tubes and the embryos are thrust down 

 again by the elongating suspensors. The observations of Schaeppi 

 and Steindl (1942), who have recently studied several other genera 

 of the family, show that in Macrosolen the upper end of the embryo 



D E 



Fig. 94. Formation of embryo sac caeca in Allium paniculatum (A-C), and Digera 

 arvensis (D, E). {A-C, after Modilewski, 192S; D-E, after Joshi, 1930.) 



sac reaches up to the base of the style, in Elythranthe it grows beyond 

 its base, in Lepeostegeres it is at about one-fourth of the height of 

 the style, in Amyema somewhere near its middle region, in Taxillus, 

 slightly above the middle, and in Helixanthera Ua just below the 

 papillate layer of the stigma. 



In other plants it is a downward growth which is more striking. 



Ua See also Johri and Maheshwari (1950). 



