embryology vs zoology

embryology

noun
  • The scientific study of embryos. 

zoology

noun
  • A treatise on this science. 

  • The part of biology relating to the animal kingdom, including the structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct. 

How often have the words embryology and zoology occurred in a corpus of books? (source: Google Ngram Viewer )