animals differ in a similar way. When the death of the animal occurs, when breathing ceases and the blood stops flowing, in the case of an animal of uniform temperature the unstable tissues at once begin to change, and they speedily lose their vital properties and die. On the other hand, in similar circumstances, the more stable tissues of an animal of variable temperature undergo but little chance for a considerable time. Thus it is that the tissues of a frog live much longer after the death of the animal than those of a rabbit, or of a rat, or of a man. The muscles live after the death of the animal. As an individual, the frog is dead. It died instantaneously and without pain, but its muscles still live, and, in suitable conditions, they may live for hours. Thus you see that the mysterious property we call life (if you choose to call it a property) is not in one part of the body more than in another, but is diffused through it. We have stopped the watch, but bits of the mechanism are still going on. By and by they will stop also, and then there will be complete death.
Now look at our preparation (see Fig. 7 p. 23). You see the muscle—the gastro-
