539 
of Edinburgh, Session 1868-69. 
3. it had been noticed by many observers that after division of 
both vagi the blood-pressure usually rises. This has always been 
ascribed to the quickened rate of cardiac action ; but the author 
proved that it is usually due to the contraction of abdominal blood- 
vessels, chiefly those of the stomach. Division of the vagi is 
followed by rise in the blood pressure — in general — only when the 
animal is digesting its food; that is, when the gastric blood-vessels 
are dilated previous to the division of the nerves. 
4. The vessels of the stomach appear to be dilated during diges- 
tion, chiefly by the vaso-inhibitory action of incident filaments of 
the vagi upon the splanchnic nerves (the vaso-motor nerves for the 
gastric vessels). 
5. By the discovery of the above fact additional support is given 
to the theory that the contractile elements of the entire vascular 
system are presided over by two kinds of nerves— one motor, the 
other inhibitory. The former brings about contraction of the 
vascular system, the latter causes its dilatation by throwing the 
vaso-motor nerves into a state of rest. 
The experiments bearing on the questions embraced in 2, 3, 4, 
and 5, were chiefly performed in 1868. 
2: On Free An-atomic or Transmissible Power. By R S. 
Wyld, Esq. [Second Paper.) 
Observations on Animal Power , its Nature and Source. And on 
Sense-perception , as a Perception of Power. 
In the first part of the paper I adduce probable, or prima facie , 
evidence in favour of the theory that the power which produces 
voluntary motion is not derived solely, nor even chiefly, from the 
decomposition of the muscular tissues, as has been generally, if 
not universally, held by recent investigators, but is derived pri- 
marily and principally from the decomposition of the cerebral 
tissues; and second, that this decomposition of the brain is effected 
by a direct voluntary mental effort. 
My views may be briefly stated in the following proposi- 
tions : — 
1st, Free force is liberated by the dissolution and decomposition 
