[ 3°6 ] 
which are joined together every-where, by one com- 
mon membrane or fubftance, called from its appear- 
ance, cellular. This fubftance, when it arrives at 
the furface of the mufcle, becomes uniform, and 
makes one intire fheath for the whole mufcle, or 
bundle of fibres, and renders it diftinct from other?. 
The conftituent fibres in many mufcles are ob- 
ferved to be partly flefhy, and partly tendinous ; the 
one changing, or being continued, into the other, 
for the conveniency of infertion and motion. But 
the obfervation is univerfal, that the flefhy fibres 
alone contract in mufcular motion, and that this 
contraction is always wave-like, or in alternate curls, 
from one extremity to the other of a given fibre. 
We constantly obferve, in every mufcle, numerous 
arteries, veins, and nerves. Thefe are generally dis- 
tributed together, or in the fame courfe, by means 
of the connecting cellular fubftance, into every point 
of the flefhy fibres. Injections, and the knife of the 
anatomift, have follow’d them a great way, and rea- 
l'on completes the diftribution, fince you can no- 
where wound the flefh of a mufcle, but it ftiall 
bleed, and witnefs a fenfe of pain. 
Therefore there is a circulation of blood, through- 
out the whole fieftiy fubftance of a mufcle : and fur- 
ther the mufcle feels in every part. 
In a living animal, if you tie the artery and vein, 
which principally belong to a given mufcle, that muf- 
cle is difabled from acting at the command of the 
will. Steno, a Danifli anatomift of the laft century, 
performed this experiment upon the defcending aorta, 
and thereby took away the ufe of all the lower limb9 
(vide Bergerum, p. 296) at once, and reftored them 
at 
