engraft vs impregnate

engraft

verb
  • To insert, as a scion of one tree or plant into another, for the purpose of propagation; graft onto a plant 

  • To fix firmly into place 

adj
  • Engrafted. 

impregnate

verb
  • To fertilize. 

  • To saturate, or infuse. 

  • To fill pores or spaces with a substance. 

  • To cause to become pregnant. 

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