MATING 



1. BIOLOGICAL FACTS. 



57 



Since organisms do not live for ever, there exist 

 various devices for reproducing them continuously. 

 Asexual reproduction occurs in one-celled organisms. 

 Its simplest form is that of division. A single cell, 



FIG. 23. FIG. 24. 



FIG. 23. DIVISION OF ASKKBA. 



A, Before division ; B, the nucleus divided ; C, the daughter 

 amoeba. 



(From Wcismann, " The Evolution Theory.") 



FIG. 24. DIVISION' OF A MARINE WORM (MYRIANIDA;. (After 

 Milne-Edwards.) 



a, Mother-individual : b to g, the daughter-individuals according to 

 their relative ages. 



(From Weismann, " The Germ-Plasm.") 



having attained a certain size, divides into two 

 daughter cells (Fig. 23). This process can be ob- 

 served in species as high as the worms (Fig. 24). 

 Another method of reproduction is that of budding. 



