MEMOIR OF BARON HALLER. 
33 
the very structure of the heart itself. The nature of 
the thing obliged me to differ in opinion from my 
preceptor. Three years afterwards I published the 
following doctrine, viz. That all animal fibres when 
they mere irritated contracted themselves; that this 
character distinguished them from those of vegetables, 
and that perpetual irritation alone mas the cause of 
the continuance of motion in the vital organs, while 
the animal organs ceased to act. In the abridgement 
of my Physiology I have positively ascribed the 
motion of the heart to the force of a stimulus; and 
in the second edition, I have been more explicit on 
the irritability of muscular fibre, asserting that it 
was independent of the nerves, and of every other 
known property. If any person denies the truth 
of this assertion, I shall be glad to learn from him 
upon what property this motion depends. Since that 
time, numerous experiments have convinced me of 
the truth of the doctrine above advanced.” 
~W e shall in this place introduce a very succinct ac- 
count of Haller s separate treatise on this interesting 
point. He divides all the parts of animals into those 
which are susceptible of irritability and sensibility, 
and those which are not. He designates irritable 
those parts which become shorter upon the applica- 
tion of a stimulus, and sensible, those which on being 
touched transmit the impression to the sentient 
being ; and, on the contrary, those are denominated 
insensible in which the most violent injuries occa- 
sion no pain or convulsive movement. These defi- 
nitions are followed by a minute examination of the 
o 
