1868 in science

Biology

• January 30 – Publication of Charles Darwin's The Variation of Animals and Plants Under Domestication, including his theory of heredity, which he calls pangenesis.
• Jules-Emile Planchon and colleagues propose Phylloxera as the cause of the Great [French Wine Blight].
• Roland Trimen reads a paper to the Linnaean Society explaining Batesian mimicry in African butterflies.
• T. H. Huxley discovers what he thinks is primordial matter and names it Bathybius haeckelii. He admits his mistake in 1871.
• The Granny Smith apple cultivar originates in Eastwood, New South Wales, Australia, from a chance seedling propagated by Maria Ann Smith.

Chemistry

• August 18 – The element later named as helium is first detected in the spectrum of the Sun's chromosphere by French astronomer Jules Janssen during a total eclipse in Guntur, India, but assumed to be sodium.
• October 20 – English astronomer Norman Lockyer observes and names the D₃ Fraunhofer line in the solar spectrum and concludes that it is caused by a hitherto unidentified element which he later names helium.
• Louis Arthur Ducos du Hauron patents methods of color photography.

Medicine

• Jean-Martin Charcot describes and names multiple sclerosis.
• Adolph Kussmaul performs the first esophagogastroduodenoscopy on a living human.

Paleontology

• March – French geologist Louis Lartet discovers the first identified skeletons of Cro-Magnon, the first anatomically modern humans, at Abri de Crô-Magnon, a rock shelter at Les Eyzies, Dordogne, France.

Technology

• June 23 – The Sholes and Glidden typewriter is patented in the United States.
• October 28 – American inventor Thomas Edison applies for his first patent, for a form of electronic voting machine.
• Ernest and Auguste Bollée first patent the Éolienne Bollée wind turbine in France.
• Scottish physicist James Clerk Maxwell's paper on governors is a landmark in the mathematics of feedback and in control theory.
• Pendulum-and-hydrostat control for the Whitehead torpedo developed by Robert Whitehead.

Awards

• Copley Medal: Charles Wheatstone
• Wollaston Medal for Geology: Carl Friedrich Naumann

Births

• January 9 – S. P. L. Sørensen, Danish chemist.
• January 31 – Theodore William Richards, American chemist, recipient of Nobel Prize in Chemistry.
• February 7 – Aleen Cust, Anglo-Irish veterinary surgeon.
• March 15 – Grace Chisholm Young, English mathematician.
• March 22 – Robert Andrews Millikan, American physicist, recipient of Nobel Prize in Physics.
• April 4
• * Philippa Fawcett, English mathematician.
• * Henrietta Swan Leavitt, American astronomer
• April 5 – Percy Furnivall, English surgeon.
• April 8 – Herbert Spencer Jennings, American zoologist.
• April 14 – Annie S. D. Maunder, née Russell, Irish astronomer.
• April 28 – Georgy Voronoy, Ukrainian mathematician.
• April 30 – J. B. Christopherson, English physician.
• May 2 – Robert W. Wood, American optical physicist.
• June 6 – Robert Falcon Scott, English explorer.
• June 7 – John Sealy Townsend, Irish mathematical physicist.
• June 14 – Karl Landsteiner, Austrian physiologist.
• July 4 – Henrietta Swan Leavitt, American astronomer.
• October 23 – Frederick W. Lanchester, English automotive engineer.
• November 8 – Felix Hausdorff, German mathematician.
• November 14 – Karl Landsteiner, Austrian-born physiologist, recipient of Nobel Prize in Physiology or Medicine.
• November 15 – Emil Racoviță, Romanian biologist, speleologist and explorer.
• November 17 – Korbinian Brodmann, German neurologist.
• December 5 – Arnold Sommerfeld, German theoretical physicist.
• December 9 – Fritz Haber, German chemist.

Deaths

• February 10 – Sir David Brewster, Scottish physicist
• February 11 – Léon Foucault, French physicist.
• February 24 – John Herapath, English physicist.
• May 22 – Julius Plücker, German mathematician and physicist.
• June 25 – Alexander Mitchell, Irish engineer and inventor of the screw-pile lighthouse.
• June 29 – Sir John Lillie, British army officer, entrepreneur and inventor
• July 15 – William T. G. Morton, American dentist.
• August 29 – Christian Friedrich Schönbein, German chemist and inventor of the fuel cell
• September 26 – August Ferdinand Möbius, German mathematician and astronomer
• December 25 – Linus Yale, Jr., American engineer and inventor.
• December 31 – James David Forbes, Scottish-born physicist, glaciologist and seismologist.