Name the Biologist - Week 20

No clues this week as he should be fairly recognisable.

As for last week's entry it was none other than Joseph Priestley - a fascinating individual whose observations that air could be "injured" by a burning candle and a mouse and "healed" by a plant was the forst step to understanding photosynthesis and respiration. He actually made a whole load of other discoveries such as oxygen and possibly his greatest contrbution was the invention of Soda water and the eraser.