OELL FORMATION BT DIVISION. 



43 



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

 plasm escapes without dividing. Rej uvenescence may then be regarded 



Fi?. 33.— Endosperm-cells of Phaeeohis muWflorus. A, the production of new cells 

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

 grtthereil around the nuclei ; &, younp cell, but without a wall of cellulose ; c-, young 

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

 endosperm in a much later stase ; ihe cells have fused their walls so as to form a 

 false tissue ; in the angles between the cells are intercellular spaces filled with some 

 of the protoplasm of the mother-cell (embryo sac) : the cell a is in process of fi-sion, 

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

 cleus ; s, line indicating the boundaries of the two masses of protoplasm ; the cell 

 5 is 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 is no division of the 

 protoplasm. 



