MATING 



59 



In sexual reproduction we have the combination 

 of two separate individuals to produce a new one. 

 The simplest way is for the two combined bodies to 



FIG. 27. BUDDING OF SPONGE COLONY. (After Haeckel.) 



(From Geddes and Thomson, " The Evolution of Sox.") 



FIG. 28. CONJUGATION OF NOCTILUCA. (After Ischikawa.) 



A, Two individuals coalescing ; B, fusion of cells ; G, beginning 

 of division ; D } completion of division. 



(From Weismann, " The Evolution Theory.") 



mingle into one, which by dividing in the asexual 

 manner produces two new individuals (Fig. 28). On 



