12 THE BREEDING OF ANIMALS 



parent cell to daughter cell and thus from parent to off- 

 spring. 



12. Anaphase. The essential step in the anaphase 

 is the separation of the two groups of chromosomes which 

 were derived from the splitting of the chromosomes of 

 the parent cell. These pass to opposite sides of the cell, 

 and in many forms these new groups begin at once to 

 assume the appearance of the original nuclear material. 



13. Telophase. Complete division of the cell is 

 finally accomplished by constriction of the parent cell- 

 walls and the formation of a new membrane which encloses 

 the two daughter nuclei each in its own cell. The two 

 groups of chromosomes derived from the parent nucleus 

 are rearranged and become the nuclei of the new daughter 

 cells which in their turn may pass through all the stages 

 described above. 



The essential steps, then, in cell division are : (1) The 

 formation of the spireme thread from the chromatin 

 and its division into chromosomes; (2) The splitting of 

 the chromosomes through the middle longitudinally; 

 (3) The movement of the divided portions of the chromo- 

 somes to the new or daughter cells. 



14. The germ-cells in detail. In all the higher forms 

 of animals, reproduction is accomplished by the forma- 

 tion of special reproductive cells called the germ-cells. 

 The germ-cells are the product of the reproductive group 

 of cells and are endowed with peculiar powers not gen- 

 erally possessed by the soma- or body-cells. Weismann 

 divided the cells of the body into two very clearly marked 

 and distinct groups, the soma- or body-cells and the germ- 

 cells. The soma-cells are primarily concerned with the 

 individual life of the animal, while the germ-cells are 

 destined solely for the purpose of reproduction. The 



