208 
Mr. Home's Lecture 
by which the motions are all produced, the machine is so 
complicated with other important or necessary parts, that 
the spring itself is not within the reach of accurate observation. 
To prosecute an inquiry into the cause of muscular motion, 
with the greatest probability of success, recourse should be had 
to muscles, which are in themselves the most simple ; and we 
should endeavour to ascertain what organization, or mecha- 
nism, is essential to this action in living animal matter, by 
which means we should acquire a previous step to the inves- 
tigation of the principle itself. 
The complex muscles in the more perfect animals, from 
their structure and application, open a wide field of inquiry ; 
for we shall find that it is from their different organizations, 
that they are enabled to perform the various actions of the body ; 
actions too powerful and extensive for muscles to effect, un- 
aided by such complication of structure, and the advantages 
derived from it. 
In the present lecture, I shall confine myself to the conside- 
ration of the most important uses of the complex structure of 
muscles, and by this means make it evident, that they are not 
indebted to it for the principle upon which muscular motion 
depends. 
These complications are necessary to supply the muscle with 
nourishment, for the continuance of its action ; to give it 
strength ; to enable it to vary its contraction from the stand- 
ard or ordinary quantity ; and to increase the effect beyond 
the absolute contraction of the muscle. How these different 
purposes are effected, I shall endeavour to explain. 
A muscle receives its nourishment from the blood, with 
which we find it more abundantly supplied than most other 
