ON THE ORIGIN OF SPECIES. OR THE PRESERVATION OF FAVOURED RACES IN THE STRUGGLE FOR LIFE.
By Charles Darwin, M.A.,
Fellow Of The Royal, Geological, Linnaean, Etc., Societies; Author Of 'Journal Of Researches During H.M.S. Beagle's Voyage Round The World.' From the First Edition LONDON: JOHN MURRAY, ALBEMARLE STREET. 1859. Down, Bromley, Kent, October 1st, 1859.
It stands for Master of Arts. Darwin received a Bachelor of Arts degree from Christ's Cambridge. Six years after a student starts at Cambridge, the title of Master of Arts is conferred upon them, as long as two years have passed since they received their B.A. Darwin originally had no intention of becoming a scientist, but instead intended to join the Anglican clergy. This wasn't actually the reason he got a B.A - that's simply the title that Cambridge gives to the the main degree in both arts and science.