146 NATURE AND LIFE. 
future of diagnosis is to be found partly here. By the ban- 
ishment from medical examination of the often-uncertain 
judgment of the senses, by substituting as far as possible 
for personal and arbitary 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 inter- 
pretation of the evil in question. Moreover, these instru- 
ments often reveal peculiarities that elude direct observa- 
tion. 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 ther- 
mometer, of variations of animal heat in diseases, ther- 
mometric clinic, as it is called, is one of the most indis- 
putable onward steps in medicine. 
Il. 
After having seen how internal heat is produced in ani- 
mals, how it expends itself in them, and undergoes change 
into mechanical work, in fine, what spontaneous or occa- 
sional 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 tem- 
perature in the medium they live in. Quite recent re- 
searches 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 fora certain length of time, 
and that the duration of resistance varies with the species. 
Small animals yield after a moderate time to a temperature 
