Who had studied medicine in youth in King Solomon's Mines?

Allan Quatermain begins the tale of his extraordinary adventures by telling us what prompted him to pick up his pen and start writing about his expedition to King Solomon's Mines. The first reason is a very simple one: Sir Henry Curtis and Captain John Good asked him to. Secondly, poor old Quatermain is laid up with a bad leg after being savagely mauled by a lion. This is no fun for anyone, least of all a man of action like Quatermain the intrepid explorer. So he has to figure out some way to pass the time before his next adventure. And what better way to do that than write about his last one?
The third reason Quatermain writes about the expedition is that he wants to provide a bit of amusement for his son, Harry. Harry is studying to be a doctor in London, and so his old man figures that reading about his adventures will provide a brief respite from the dull routine of hospital life.