Structure, etc., of Epiphegus Virginiana. 387 



are rather smaller and paler than any of the other nuclei in 

 the embryo sac or macrospore cavity. 



In the next older stage, the ovule is seen increased much 

 in length, but little wider. Starch is appearing in the walls 

 of the outer seed-coat. At the micropylar end, a long, nar- 

 row neck is left between the seed-coats. Below this lie the 

 remains of the old embryo sac, still showing the two syner- 

 gidse above the egg nucleus. A break occurs just below, 

 and then is seen a vertical row of six to eight cells, larger 

 below, smallest next the egg. This is the precocious albu- 

 men or endosperm, formed by division of the endosperm 

 nucleus prior to fertilization. These cells are densely pro- 

 toplasmic, and show a fairly large nucleus and nucleolus. 

 They are separated from the cells of the seed-coats by a 

 thick stained membrane. 



In ovules observed at about the stage of fertilization, a 

 great increase has taken place in the amount of endosperm 

 cells. Three or four long rows of cells are present, formed 

 by divisions which have been observed occurring in both 

 directions. The spindles formed are remarkably broad and 

 barrel-shaped in form. These endosperm cells have grown 

 up around and above the egg cell, and form a structure 

 resembling an archigonial neck below the micropyle, having 

 pushed apart the seed-coats. Down this neck the pollen 

 tube is seen passing to the egg cell. It is faintly stained 

 and almost transparent, containing little cytoplasm. The 

 process of fertilization was not observed. After the egg 

 has been fertilized, there is always observed a second degen- 

 erating nucleus lying in the pollen tube just above the egg 

 cell. This is probably the second sperm nucleus that in 

 many plants has been found to unite with the endosperm 

 nucleus. But here, the endosperm nucleus has already 

 divided and formed the precocious albumen, so this sperm 

 nucleus would necessarily be non-functional. 



The first cleavage wall divides the egg in horizontal direc- 

 tion. The upper cell is smaller, both in the size of the 



