physiology vs taxonomy

physiology

noun
  • A branch of biology that deals with the functions and activities of life or of living matter (as organs, tissues, or cells) and of the physical and chemical phenomena involved. 

taxonomy

noun
  • The science of finding, describing, classifying and naming organisms. 

  • The science or the technique used to make a classification. 

  • A classification; especially, a classification in a hierarchical system. 

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