THE HORMONES IN HUMAN REPRODUCTION 



squeamish about the whole matter of reproduction by phy- 

 sical contact of the sexes : 



I could be content that we might procreate like trees, 

 without conjunction, or that there were any way to per- 

 petuate the World without this trivial and vulgar way 

 of union. 



RELIGIO MEDICI. 



In illustration of these roving thoughts of poet and scien- 

 tist, let us return for a moment to the sea-born Cothurnia. 

 When such an animalcule reproduces itself by division, we 

 find it handy to call the new animal a "daughter cell," but 

 this is only a figure of speech. The offspring is even closer 

 than a child ; it is more truly a twin of the cell that produced 

 it, for their relationship is exactly like that between a pair 

 of human identical twins, which arise by the splitting of one 

 cell, i.e. the human egg. Presently the parent Cothurnia will 

 give off another "daughter cell" ; will that be niece or sister 

 of the first? And if a Cothurnia is sister to its mother (i.e. 

 the cell that produced it) is it not equally sister to its grand- 

 mother . . . and so on, as far back as the line was reproducing 

 by simple division? We have here indeed a situation in which 

 the terminology of the human bisexual family tree breaks 

 down, for all the offspring of a single cell that reproduces 

 without mating are related together even more closely than 

 the members of a human family. They all have identically the 

 same heredity, and are all "twins" one of another, though 

 they may number thousands and represent many "genera- 

 tions." For this kind of group the biologists have had to 

 invent a new name; they call it a clone. 



Such a clone, being a group of cells that all came from one 

 cell, may be considered something like the body of an indi- 

 vidual many-celled animal. That too is a group of cells that 

 all came from one cell. Like an animal body the clone seems 

 to have its phases of youth, maturity, and old age. After 



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