It is possible, however, to have a temperature which even a Hindoo cannot resist. When a man is exposed to such a heat his bodily temperature rises, and as it rises the symptoms of fever develop precisely as they do in the lower animals--sometimes slowly, sometimes suddenly--with disturbances of the respiration, circulation and innervation precisely similar to those already noticed as occurring in the dog, the cat and the rabbit. Sunstroke, or thermic fever, is generally believed to be instantaneous in its onset, but the wide experience of the English in India has shown that whilst in some cases it is thus sudden in its development, in others it is a slow process, and probably in almost all cases close observation would have revealed the existence of premonitions. External heat, by producing an internal rise of temperature, may thus cause all the phenomena of fever. Of these phenomena the most prominent is disturbance of the nervous system and of the circulation. In order to determine whether the heat itself directly causes the nervous disturbance, or whether it produces it indirectly by causing changes in the blood, I applied caloric directly to the brains of animals. This was done by fitting a hog's bladder like a bonnet over the head and allowing hot water to run through it. It was found that stupor, coma, convulsions, and finally death from arrest of the respiration, were produced, sometimes gradually, sometimes suddenly, precisely as in the case of exposure of the animal in a hot chamber. Moreover, on opening the skull and plunging a thermometer into the cerebrum immediately after death or the supervention of unconsciousness, it was found that these phenomena were developed at the same brain-temperature when the heat was locally applied as when the animal was exposed in the hot box. Thus, if any given species in the hot box became unconscious when the temperature reached 110° Fahrenheit, this species also became unconscious when the locally-heated brain attained a temperature of 110°; or if death occurred by arrest of the respiration in the hot box at 114°, so did it when the locally-heated brain reached that point. Dr. Lauder Brunton of England has performed a series of experiments upon the circulation parallel to those just narrated. Anæsthetizing animals and exposing the heart, he has found that the action of that organ is accelerated and weakened by the local application of heat, precisely as occurs in fever. In order to test the effect of the withdrawal of heat, I have taken a rabbit out of the hot chamber, in which it lay upon its side totally unconscious, and plunged it into a bucket of cold water. The temperature of the water rose rapidly, whilst that of the rabbit fell even more rapidly. As soon as the bodily heat approached its normal intensity consciousness returned, and in a few moments the animal, which had just before been at the point of death, was running about the grass.