Chullin 46 - The Spine, The Liver, and The Lung
If the spine was broken and its cord severed - the animal is a terefah. Rabbi Yehudah the Prince says that the majority of the spinal cord must be severed, but Rabbi Yakov says that even if the spinal cord was merely punctured - the animal is a terefah. Rabbi Yehudah ruled stringently in practice, like Rabbi Yakov, but the law is like Rabbi Yehudah's own lenient view.
If the liver was removed and nothing remained of it - the animal is a terefah. Elsewhere we learned that if less than an olive-volume remains, it is a terefah. Which is right? The opinion that requires an olive-volume belongs to Shimon the son of Rabbi Yehudah. He considered liver an organ important for the animal, therefore a healthy food, and ate it. Rabbi Chiya is the one who held that any remaining piece of the liver is sufficient. He considered the liver not such an important organ, not a healthy food, and threw it away.
If the lung was punctured in both membranes, the animal is a terefah. The lung can be examined by blowing it or by submerging it in warm water.
Art: Juan Bautista de Espinosa - Still Life Of Fruits And A Plate Of Olives