Louis E. Pratt, master ivory cutter for Pratt, Read & Co., shows off eight ivory tusks, April 1, 1955. Courtesy of Deep River Historical Society hide caption

itoggle caption Courtesy of Deep River Historical Society

Asian carp, battered and fried. As the fish makes its unwelcome way up the Mississippi River, chefs are trying to get people to eat to beat it back. Louisiana Sea Grant/Flickr hide caption

itoggle caption Louisiana Sea Grant/Flickr

Angelo Mosso's "human circulation balance" machine worked like a seesaw to measure blood flow changes to the brain. Stefano Sandrone et al., Brain hide caption

itoggle caption Stefano Sandrone et al., Brain