io8 Introduction to Botany. 



partition wall, and so on. In this process the parent cell 

 must distribute to the two daughter cells resulting from its 

 division all of the qualities and powers possessed by itself ; 

 and to accomplish this it is important that the division of 

 the nucleus in particular should be equal, one daughter 

 cell receiving neither more nor less than the other. We 

 are able to see, in following the steps in the division of a 

 cell, that the equal partition of the nucleus is actually 

 accomplished with astonishing care (see Fig. 46). 



The' nucleus becomes threadlike in structure (i); the 

 thread is divided longitudinally through the middle, and 

 then the double thread is broken transversely into several 

 double rods (2); the double rods are now grouped at the 

 equator of the cell, namely, at the central plane, where the 

 dividing wall is to be formed (3 and 4) ; then the two halves 

 of each double rod are drawn apart to opposite poles of the 

 mother cell (5, 6, and 7), where they fuse together to form 

 two daughter nuclei (8). Finally a wall is formed which 

 cuts the mother cell into two daughter cells (8 and 9). This 

 will serve as a general statement, but the details of the 

 process are so wonderful that they have been given more 

 fully in the description of the figure. 



If we go back to the beginning in the life history of one 

 of the higher plants, we find that it is, at first, a fertilized 

 egg cell, of which we shall learn more in the chapter on 

 the flower. The plant has, therefore, its beginning in a 

 single minute cell ; this divides, and its offspring in their 

 turn divide, until the whole plant body, consisting of mil- 

 lions of cells, is formed by its descendants. 



83. Cell Growth. After the cells have divided, the 

 daughter cells increase in size, and not till then does an 

 enlargement of the plant take place. The increase in size 

 of the cells is brought. about by absorption of water until 



