COURTSHIP i8i 



The " reproduction," or producing of new individuals, 

 of many animals and plants can be, and is, effected by 

 the detachment of large pieces of a parent organism. 

 Thus plants split into two or more pieces, each of which 

 carries on life as a new individual. Many worms and 

 polyps multiply by breaking into two or more pieces, 

 and very often the broken-off pieces which thus become 

 new individuals and carry on the race are extremely 

 small, even microscopic in size. The spores of ferns and 

 the minute separable buds of many plants and animals 

 are of this nature. They grov\r into new individuals 

 without any fusion with fertilizing particles from another 

 individual. Yet there seems to be even in the very 

 simplest living things a need to be met, an advantage to 

 be gained, in the fusion of the substance of two distinct 

 parents in order to carry on the race with the best chance 

 of success. We find that those organisms which can 

 multiply by buds and fission yet also multiply regularly 

 by ovules fertilized by sperms. We see this process in 

 its simplest condition in microscopic plants and animals 

 which are so minute that they consist of only a single 

 "' cell " — a single nucleated particle of protoplasm. Such 

 unicellular organisms have definite shape, even limb-like 

 locomotor organs, shells, contractile heart-like cavities 

 within the protoplasm, even mouths, digestive tract, and 

 a vent. They produce new individuals by merely 

 dividing into two equal halves or by more rapidly 

 dividing into several individuals each like the parent, 

 only smaller. But from time to time, at recurring 

 periods or seasons, two of these unicellular individuals 

 (of course, two of the same kind or species) come into 

 contact with one another, not by mere chance, but 

 attracted and impelled (probably by chemical guiding or 

 alluring substances of the nature of perfumes) towards 

 one another, and then fuse into one. Two (or sometimes 



