THE HORMONES IN HUMAN REPRODUCTION 



Fio. 1. The one-celled animal Cothurnia, reproducing itself by simple 

 division. The parent animal is seen at a. From 6 to d, successive stages 

 of division. In e the daughter cell has freed itself and is swimming away, 

 to settle in a new location. Greatly magnified. 



down upon a near-by strand of seaweed, or perhaps (ventur- 

 ing greatly) as far away as the next timber of the wharf. 



All this makes no difference to the first cell; it undergoes 

 no pregnancy, feels no pangs while giving birth and takes 

 no responsibility to nurse, guard, or educate its offspring. 

 The latter in turn asks nothing at all of its parent, and never 

 realizes the disadvantages of birth at so low a level of organi- 

 zation, one of which is that the newborn cell faces immediately 

 and alone all the dangers of its world. The infant mortality 

 of Cothurnia must be enormous, for there are many enemies 

 and risks, but what of that.? The parent can easily split off 

 another cell, and in spite of the wastage it is more economical 

 (if all you want is a one-celled child) to breed by excess pro- 

 duction than by the intricate process through which man 

 and the higher animals turn out their limited output of 

 complex and troublesome offspring. 



Other unicellular animals have developed variations of the 

 process of reproduction by division. Sometimes they do not 

 divide into two equal cells, but put out their daughter cells as 

 mere buds which break off while small and only later reach 



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