CELL FORMATION BY DIVISION. 



4..'! 



one mass before escaping ; while in Rejuvenescence the whole proto- 

 plasm escapes without dividing. Rej uvenescence may then be regarded 



Fi2. 33. Endosperm-cells of Phaseolus multiflorus. A, the production of new cells 

 in the protoplasm of the embryo sac ; n, n, n, nuclei ; a, a, a, masses of protoplasm 

 gathered around the nuclei ; b, young cell, but without a wall of cellulose ; c, young 

 cell with a wall ; c', d, young cells with walls and vacnoles. B, two cells of the 

 endosperm in a much later stare ; the cells have fused their walls so as to form a 

 false tissue ; in the angles between the cells are intercellular cpac^s filled with some 

 of the protoplasm of the mother-cell (embryo sac) ; the cell n is in process of fission, 

 the two nuclei n, n, are near together, as if formed by the flss'on of the original nu- 

 cleus ; ,, line indicating the boundaries of the two masses of pn.toplasm; the cell 

 b \* fully divided, and the two parts are sep irated by the wall cl. X 670. After 

 Dippel. 



as a case of internal cell-formation in which there ia no division of the 

 protoplasm. 



