354 THE HORSE. 
useful as affording an agent for this purpose of much less compass than 
muscle itself, and also of a structure not so easily injured by external 
violence. Thus they are generally met with around the joints, the nus 
cular substance chiefly occupying the space between them. ‘There are 
three varieties of tendon—l. Funicular, consisting of cord-like bands ; 
2. Fascicular, including bands of a flatter and more expanded nature ; 
and 3. Aponeurotic, which are membranous, and are chiefly met with 
around the abdomen. ‘The fibres are firmly attached to the bones, which 
generally present rough surfaces for this purpose, and are also closely 
incorporated with the periosteum. ‘This union is so strong, that it very 
rarely gives way; and when extreme violence is used, either the bone ' 
itself breaks, or the tendon snaps in its middle. Tendons are non-elastic. 
To THE NAKED EYE, an ordinary muscle appears to be composed of a 
number of small bundles of fibres, arranged in parallel lnes, and con- 
nected by a fine membrane. These bundles may still further be separated 
into what secm at first to be elementary fibres; but when placed in the 
microscope, they are found to be themselves made up of finer fibres united 
into fasciculi by delicate filaments. These ultimate fibrillee are polyhedral 
in section, according to the observations of Mr. Bowman, so as to pack 
closely together, and are variable in size in different classes and genera of 
animals. They also differ in appearance, one class presenting stripes 
while the other is without them. The former includes all the muscles 
whose movements are under the control of the will as well as those of the 
heart, and some of the fibres of the cesophagus, while the latter is com- 
posed of the muscles investing the stomach, intestines, bladder, &c., 
which are comprehended under the general term involuntary. 
Tue SarcoLemMa is the name given by Mr. Bowman to the areolar 
tissue investing each fibre, sometimes also called myolemma. It is very 
delicate and transparent, but tough and elastic ; in general it has no appear- 
ance of any specific structure, but sometimes it presents an aspect as if 
there was an interweaving of filaments. 
WHEN A FIBRILLA of striated muscle is examined under the microscope 
of a high magnifying power, it is seen to present a beaded appearance, as 
if made up of a linear aggregation of distinct cells, alternately light and 
dark. When the fibrilla is relaxed, each cell is longer than it is broad ; 
but, during the action of the muscle, it assumes the opposite dimensions, 
the increase in one diameter being always in proportion to the diminution 
of the other. As the contraction takes place the substance becomes firmer 
than before, but the bulk remains the same, the mass merely gaining in 
thickness what it has lost in length. The application of certain stimu- 
lating agents will produce the contraction for a certain period after life 
is destroyed, varying according to the vitality of the animal experimented 
upon and the nature of the individual muscle. This is called writability 
in the striated muscles, which exhibit powerful contractions, alternating 
with relaxations—while in the involuntary muscles a more steady, per- 
manent, and moderate contraction is met with, to which the name of 
tonicity has been given. 
PURE MUSCULAR FIBRE appears to be identical in composition with the 
fibrine of the blood, being made up of about seventy-seven parts water, 
fifteen and a half parts fibrine, and seven and a half parts of fixed salts. The 
whole of the flesh of the body is largely supplied with blood, and it is 
found by experiment, on the one hand, that if this is cut off contraction 
ceases very speedily after; and on the other, that in proportion to the 
amount of muscular action will be the demand for fresh supplies of blood. 
