Control and communication > rate

To investigate the action of a working heart, and conduct experiments on it, needs an animal larger than Daphnia. Frogs were used in the past for such physiological work, because their tissues remain active for some time after the animal has been killed. It is possible to kill a frog in such a way as to leave its heart still functioning (this is called pithing). This is now an illegal practice in schools. This is an opportunity to discuss the