CARPEL IN THE DATE. Ill 



change position as much as the endostome, which retains 

 its topographic relation to the embryo. As a condition of 

 further growth, there is yet but little differentiation in the 

 integuments. There is growth in thickness and extent, 

 the cells retain their undifferentiated character. 



but 



Stage III. Close of the Second Period. 



- 



Carpel. Aside from the extension of the tissues by growth, 

 there is little to record, except only that, as a result of the 

 mutual pressure of tissues, the inner zone of the carpel 

 becomes slightly compressed. A small amount of disoreran- 



d 



endocarp. The 



more 



where, and it is especially noticeable in its effects upon the 

 placental sulci, which become distorted. The contingent 

 cells within the sulcus become denser in character and there 

 appears as it were a mucilaginous thickening of some of the 

 cell walls, especially near the meatus. There are numerous 

 tannin cells of idioplastic nature, though the tannin is not 

 wholly confined to these. 



Seed. In the seed the greatest change is in the inward 

 growth of the endosperm, and its extension backward bevond 



the secondary chalaza. 



proceeds 



first at the chalaza (f. 10) filling the cul-de-sac; the inwardl 





mo\ 



gressing toward the opposite (micropylar) pole of the em- 

 bryo sac. All nutritive changes in the endosperm progress, 

 similarly, from the chalaza toward the micropylar pole. 

 When the space is entirely filled, and before secondary 

 changes set in, the endosperm cells are very thin walled, with 

 the nucleus suspended in the middle of the cell by numer- 

 ous radiating protoplasmic threads. They are isodiametri^ 

 but their radial measurements begin to increase rapidly, con- 

 currently with the later growth of the seed. The growth 

 of the integuments is very rapid, in view of the rapid 

 increase in volume of the seed, and their definitive characters 

 are still absent. 





