THE HUMAN BODY. 



network of minute blood-vessels. Where a muscle tapers 

 the muscle fibres in the fasciculi are less numerous and when 

 a tendon is formed they disappear alto- 

 gether, leaving only the connective tissue. 



Histology of Muscle. The striped mus- 

 cular tissue, which gives the muscle its 

 power of contracting, is found when ex- 

 amined by the microscope to be made up 

 of extremely slender muscular fibres, each 

 about one inch in length, but most of 

 them less than -5^5- of an inch across. 



Each muscular fibre has externally a 

 thin sheath or envelope, the sarcolemma, 

 which envelops the contracting part of tho 

 fibre. This latter is soft and almost 

 FIO. 33. A small semi-fluid, and under a microscope is seen 



piece of muscular . 



fibre highly mag- i,o present a striped appeariincc. as if 



nified. At a the 



fibre has been made up of alternating dimmer and 



crushed and twist- 



ed so as to tear brighter transverse bands (Fig. 33). 



its contents, while \ 9 



k3mma ghc eir< r -' Affcer death tne semi-solid contents of the 

 Suited tlSS fibre solidif y and death -stiffening is pro- 

 Smains 6 unttrn duced ; at the same time the fibre often 



and conspicuous. gplitg up .^ ft number of very fine 



threads or fibrillcs, which were formerly regarded as true 

 constituents of the living muscular fibre. 



Plain muscular tissue. The muscles hitherto spoken of 



Of what is a tendon made ? 



Of what is striped muscular tissue composed ? Describe the form 

 and size of muscular fibres ? 



What is the sarcolemma? What is the consistency of the con- 

 tractile part of a living muscular fibre? What appearance does it 

 present under the microscope? What is the cause of death stiffening? 

 What are fibrillse ? 



What do we mean by voluntary muscles ? 



