Issue 7 : Hound, Chapters 9

And yet the course of true love does not run quite as smoothly as one would under the circumstances expect.
A reference to Shakespeare's A Midsummer Night's Dream: "The course of true love never did run smooth."

…there was thrust out an evil yellow face, a terrible animal face, all seamed and scored with vile passions.
Like Dr. Mortimer, Watson apparently believes that there is a criminal "type"—a throwback to a less evolved human being who is closer to our animal origins.

Late nineteenth-century criminology focused on the vain hope that criminals could be recognized by certain physical traits. Cesare Lombroso (1835-1909), Italian scientist, first developed his theory of the "born," or "atavistic," criminal in 1872. Lombroso believed that this type of criminal was a throwback to an earlier stage of evolution—the Neanderthal—both physically and psychologically, and therefore lacked an ethical sense. The criminal's face and body were marked by what Lombroso called "stigmata."

Other researchers often had trouble reproducing Lombroso's results, probably because his methods were slipshod. In The Female Offender Lombroso complains that no one but he could find 33 "criminal anomalies" in the dimensions of the skull of Charlotte Corday, murderer of Marat.

Lombroso's measurements of the skulls of female criminals and prostitutes
Skull of Charlotte Corday

Through the years, Lombroso tried to modify his theory to go beyond biology by taking account of environmental, social, and psychological factors; however, his work remained flawed by his preconceptions of what criminality meant. He defined criminals as people who were already in jail, and never compared them to the general population in order to test his theory. His writings had a great influence on the American criminal justice system, but today are no longer taken seriously, except as a historical curiosity. Towards the end of his life, Lombroso—like Conan Doyle—became an ardent spiritualist.

The idea that criminals possess a low forehead and other "primitive" physical characteristics was influenced heavily by phrenology and anthropometry. Such ideas also surfaced in the literature of the time.

"He is not easy to describe. There is something wrong with his appearance, something displeasing, something downright detestable. I never saw a man I so disliked, and yet I scarce know why. He must be deformed somewhere…."
—from a description of Mr. Hyde (The Strange Case of Dr. Jekyll and Mr. Hyde by Robert Louis Stevenson, 1886)

In Stevenson's story, Mr. Hyde is Dr. Jekyll's atavistic self

I caught one glimpse of his short, squat, strongly-built figure as he sprang to his feet and turned to run. At the same moment by a lucky chance the moon broke through the clouds. We rushed over the brow of the hill, and there was our man running with great speed down the other side, springing over the stones in his way with the activity of a mountain goat.
Selden's atavism has advantages—he is able to outrun his more "civilized" pursuers.

A lucky long shot of my revolver might have crippled him, but I had brought it only to defend myself if attacked, and not to shoot an unarmed man who was running away.
Like Conan Doyle himself, Watson follows a chivalric code of honor, even when it does not work to his advantage. Watson often brings his "service revolver" on cases at Homes's request, but he hardly ever fires it.