haemoglobulin vs hemoglobin

haemoglobulin

hemoglobin

noun
  • The iron-containing substance in red blood cells that transports oxygen from the lungs to the rest of the body; it consists of a protein (globulin), and haem (a porphyrin ring with an atom of iron at its centre). 

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