Newt
Newts, as with salamanders in general and other amphibians, serve as bioindicators because of their thin, sensitive skin and evidence of their presence (or absence) can serve as an indicator of the health of the environment. Most species are highly sensitive to subtle changes in the pH level of the streams and lakes where they live. Because their skin is permeable to water, they absorb oxygen and other substances they need through their skin. Scientists study the stability of the amphibian population when studying the water quality of a particular body of water.
Tweedy John Todd
Todd began experiments on healing using newts at the British Naval base in Naples, and continued when he moved to Brighton. He conducted a series of experiments on the newts and other animals such as worms to study the processes of healing and regeneration of wounds and amputated body parts. These were the first experiments that proved that nerves have a role in healing, and that amphibian limbs cannot regenerate if the nerves are cut. He observed the healing process microscopically and collaborated with histologist Charles Ager to produce over 3,000 microscope slides to illustrate his findings. These slides are amongst the earliest surviving examples of the use of Canada balsam as a mountant.