Etymologically, Vivisection refers to the dissection of, or any cutting or surgery upon, a living organism. More generally, it is used to describe any invasive experiment upon living animals, or any live animal testing, typically for the purpose of physiological or pathological scientific investigation. The term is most commonly used by opponents of animal research.
Vivisection has been controversial since the 19th century with physiologists expressing reservations much earlier. Sides, for and against, have formed over the years and are often deeply entrenched in their respective viewpoints. In 1655, physiologist Edmund O'Meara is recorded as saying that "the miserable torture of vivisection surely places the body in an unnatural state." citation needed] O'Meara thus expresses one of the chief scientific objections to vivisection, that the pain of the vivisected subject will interfere with the accuracy of the results. On the other side of the debate, those in favor of vivisection hold that experiments on living animals are necessary to advance medical and biological knowledge.