suddenly to 36° or even 35°, while, in the attack that takes the form of apoplexy, it continues nearly at 38°. These two disorders, quite distinct in their treatment and cure, yet often give rise to a confusion, which the thermometer will hereafter allow to be avoided. Granular meningitis is distinguished from simple meningitis by the same method; in the former the temperature does not rise, notwithstanding the extreme rapidity of the pulse, but in the latter the thermometer marks 40° or 41°.
In every case we see what advantage practical medicine may gain from the physical sciences, what precision and safety it attains by the employment of its means, in proportion to the morbid symptoms. We may add that the future of diagnosis is to be found partly here. By the banishment from medical examination of the often-uncertain judgment of the senses, by substituting as far as possible for personal and arbitrary conclusions, as well as for the feeling, always more or less confused, of the physician, the plain and impassive indications of an exact instrument, we do away with the causes that impede the methodical interpretation of the evil in question. Moreover, these instruments often reveal peculiarities that elude direct observation. They repair the omissions, correct the mistakes, guide the activity, multiply the power of our imperfect senses. From this point of view, the study, by the thermometer, of variations of animal heat in diseases, thermometric clinic, as it is called, is one of the most indisputable onward steps in medicine.
III.
After having seen how internal heat is produced in animals, how it expends itself in them, and undergoes change into mechanical work, in fine, what spontaneous or occasional changes it passes through in them, we should study the influence of external heat on the same animals, and the various phenomena resulting from the rise or fall of temperature in the medium they live in. Quite recent researches have thrown light on these questions. Boerhaave had made some experiments, not sufficiently exact, however, on the subject. Berger and Delaroche, at the beginning of this century, undertook new ones, which gained celebrity in the schools of physiology. They placed animals in stoves containing air heated to different degrees of temperature, and noted the effects produced on life by thermic influences. The conclusion from their researches was, that all animals have the power of resisting heat for a certain length of time, and that the duration of resistance varies with the species. Small animals yield after a moderate time to a temperature of 45° to 50° (cent.). Larger ones endure heat better. Cold-blooded animals and the larva? of insects resist more energetically than warm-blooded animals; but the reverse is the case with fully-developed insects.
Delaroche and Berger studied the human subject, too, from the
