1. Stimulation of the central end of the vagus and
injection of acetyl choline in the ventricles of the
brain have a similar effect on respiration, namely
a marked depression of respiratory movements.
2. Atropine and physostigmine do not modify the
effect of central vagal stimulation or intraventricular acetyl choline injection.
3. In a small proportion of cases an acetyl-cholinelike substance appears in the cerebro- spinal fluid
after stimulation of the central end of the vagus
when no such substance is present in the normal
4. The physiological and physico -chemical
properties of the brain extracts of cats and rabbits
show a close resemblance to the properties of acetyl
5. Various biological tests applied to the brain
extracts show that acetyl choline is normally presents
in the brain.
6. The concentration of acetyl choline is highest i
the basal ganglia, and lowest in the cerebellum;
!the concentration in the cortex is slightly lower
than that in the basal ganglia.
7.. The acetyl choline equivalent in the basal ganglia,
is about 0.44 y in cats and about 0.14γ in rabbit's.
8. It is suggested that the effects of stimulation
of the central end of the vagus are due to liberation'
of acetyl choline in the central nervous system.