Having studied the spinal marrow, the physiologist, leaving this untouched, cuts off the upper brain of the frog, leaving the lower brain in union with the spinal cord, and unharmed. A frog so mutilated, sitting upon a leaf or tuft of grass in a swamp, would be apt to be passed unnoticed as anything extraordinary. He sits perfectly still when approached, but touch him and he leaps off vigorously. If an obstacle be in the way, he does not strike it, but springs above, below or to one side as circumstances may favor. If dropped into the water, he swims as well as ever, and if the water be gradually heated, he soon endeavors to get out. If, as he sits upon a board, the latter be quietly and not too suddenly moved, he does not jump away, but continually shifts his position, so as to maintain the centre of gravity in its proper place and to keep the normal erect posture. Stroke the back of the frog gently and he croaks responsively, as if the titillation called back pleasant memories of caresses received in some lover's tussock-bower. The answer to the stroking is so certain that, as suggested by Goltz, a chorus of brainless frogs might be obtained whose batrachian voices would delight the nerves of old Aristophanes with a triumphal burst of _Brekekekéx! koáx! koáx!_ Many other things will the brained frog do--almost enough to convince a superficial observer that the cerebral hemispheres are a luxurious superfluity to the physical and mental well-being of the average inhabitant of the swamp. But no. A little watching shows that for this seemingly intelligent creature past, present and future are alike blotted out. Let the frog alone and it sits motionless, buried not in the profundity of its thoughts, but in the abyss of its thoughtlessness. In the midst of abundance it starves--not, like Tantalus, because it cannot gratify its desires, but because it has no desires to gratify. It feels no hunger, or if it feels hunger seeks no food. A perfect automaton, it moves when touched, it croaks when stroked, it answers to a multitude of external irritations, but when untouched and left to itself it is as a lifeless clod until the sun dries it up and the winds blow it away. The fish whose cerebral hemispheres or upper brain has been taken away has, like the frog, all conscious perception blotted out, but, unlike the frog, it is in perpetual motion. Stopping not for food, it rushes through the water, avoiding obstacles, but never ceasing its mad race until muscle-power or nerve-force fails because of excessive use and lack of nourishment.