THE BRIDGE OF LIFE 



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which possessed the ability to give form to a new human life. A 

 woman's menstrual fluid was supposed to be the female semen, but she 

 did not have the power to achieve the same high degree of purification 

 characteristic of man. When these two fluids combined, as he assumed 

 they did during intercourse, the semen of the man was supposed to give 

 form to the embryo, while that of the woman was supposed to furnish 

 the substance from which the embryo was formed. 



From Genetics, Winchester, Houghton Mifflin 



Fig. 31.1. Preformation. Some men of the seventeenth century imagined that they 



could see miniature human embryos within human sperms. These are drawings after 



Hartsoeker, 1694, on the left, and after Dalempatius, 1699, on the right. 



Other great thinkers of the ancient Greeks added to this the thought 

 that the semen from both man and woman originated from the body 

 parts which they were to form. In other words, the hands of a man 

 would produce semen which would migrate to the reproductive organs 

 where it would mingle with semen produced by the other body parts. 

 When introduced into the body of a woman, it would stimulate the 

 formation of hands in the embryo which would resemble those of the 

 person from which the semen originated. Through this supposed 



