With the nitrite of amyl, Dr. Richardson has suspended the life of a frog for nine days, yet the creature was then restored to full and vigorous life. He has shown also that the same power of suspension, though in less degree, "could be produced in warm-blooded animals, and that the heart of a warm-blooded animal would contract for a period of eighteen hours after apparent death." The action of nitrite of amyl seems to resemble that of cold. In the pleasing language of the doctors, "it prevents the pectous change of colloidal matter, and so prevents _rigor mortis_, coagulation of blood, and solidification of nervous centres and cords." So long as this change is prevented, active life can be restored. But when in these experiments "the pectous change occurred, all was over, and resolution into new forms of matter by putrefaction was the result." From the analogy of some of the symptoms resulting from the use of nitrite of amyl with the symptoms of catalepsy, Dr. Richardson has "ventured to suggest that under some abnormal conditions the human body itself, in its own chemistry, may produce an agent which causes the suspended life observed during the cataleptic condition." The suggestion has an interest apart from the question of the possibility of safely suspending animation for considerable periods of time: it might be possible to detect the nature of the agent thus produced by the chemistry of the human body (if the theory is correct), and thus to learn how its power might be counteracted.