CELL XOBMATION BY DIVISIOJST. 



43 



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

 plasm escapes without dividing. Rejuvenescence may then be regarded 



Pig. 33. — Endosperm-cells of Phaseolua wuWfiorus. A, the production of new cells 

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

 gathered around the nuclei ; ft, younp cell, hut without a wall of cellulose ; c, young 

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

 end08;)erm in a much later stane ; ihe cells have fused their walls so as to form a 

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

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

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

 cleus ; 8i line iudicaling the boundaries of the two masses of protoplasm ; the cell 

 S is fully divided, and the two parts are sep iiated by the wall cl. X 670.— After 

 Dippel. 



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

 protoplasm. 



