This is a specimen of Pig liver. The Pig liver is the largest visceral organ and early anatomists, called it the "liver" thinking that it must be important because of its large size though they didn't know what its function was. The liver is distinctive because of its ability to regenerate.

This slide was purchased on Ebay and is part of 100 prepared slides " set A" I believe you'll find these images of Pig liver to be superior to those found elsewhere!