lymphatic system vs lymphonodus

lymphatic system

noun
  • In mammals, including humans, a network of lymph vessels and lymph nodes that transport fluid, fats, proteins, and lymphocytes to the bloodstream as lymph, and remove microorganisms and other debris from tissues. 

lymphonodus

noun
  • Synonym of lymph node. 

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