528 



THE MICROSCOPE. 



materials for building up animal structures are furnished 

 from the yelk and the blood. 



The nucleated cell, fig. 269, No. 1, is a delicate mem- 

 brane of a globular form, enclosing a granulous fluid; in the 



Fig. 269. Diagram showing the development of Animal Cells. 



1, Shows a newly formed cell. 2, Subdivision of the nucleus. 3, The nucleus 

 changes its situation, and at 4, subdivides and disappears. 5, The walls of 

 the cell increase in thickness. 6, The cell becomes branched, or stellate. 

 7, Two cells are seen to coalesce. 8, They have coalesced and run into each 

 other. 9, Again they take another form and become multilocular. 10, 11, 12, 

 Cells sprouting out to form membrane and vessels. 14, Development of com- 

 plicated cells, which at 13, have coalesced to form tissue. 



wall of which is an oval body somewhat darker than the 

 rest this is the nucleus : there are one or two, seldom 

 more; these enclose central spots, termed the nucleoli. 

 The size of a cell may be l-300th part of an inch in 

 diameter, some are larger, some smaller; the nucleus may 

 be l-3000th of an inch in diameter; the nucleolus 

 1-1 0,000th of an inch in diameter, more or less. 



