TIIK Ml'SCf'LAR sysTE.\f 15 



luiioii of muscles and siieli ;i inusclc or muscle gr()U{) is known as 

 the aritagonid of its opponent. The application of this principle 

 facilitates the study of muscles to a considerable decree. The 

 contraction of a nuiscle is in the direction of the lonjj; axes of its 

 fibers which serves as an index to the particular work which a 

 ^iven muscle or group of nuiscles may perform in producing 

 movement in any part of the body. 



Remove the skin from l)oth the body and its appendages. In 

 doing so it will be noted that over the greater part of the body the 

 skin is not attached to underlying parts but that along certain 

 narrow lines there are firm attachments which must be cut in 

 order to free the skin. This forms underneath the skin great 

 spaces circumscribed by the lines of attachment. These spaces 

 in the living frog are filled with lymph and from their location 

 and contents are termed subdermal lymph spaces. 



The removal of the skin exposes the superficial muscles of the 

 body. The muscle masses may be improved for study by rinsing 

 in a current of water and at the same time brushing the surface 

 with a wad of absorbent cotton. During the progress of the 

 study keep the muscles moist. 



A study of the muscles is not difficult but requires careful 

 observation and thought. It is necessary to see what you look 

 at and think about what you see. 



Manipulate the body of a live frog or one recently killed and 

 determine those places where there is the greatest amount of move- 

 ment or flexibility. A list of such places will be found convenient 

 for later use. Observing the dorsal surface of the frog one notes 

 that in certain places the muscles are massed while in others they 

 are almost absent. Considering the dorsum of the body and the 

 arm and leg of one side only, excluding hand and foot, there are 

 six of these masses. Identify and give each a name which will 

 indicate its location and so label the proper figure of the plate 

 representing the superficial (surface) muscles. Determine and 

 express the relation of these nmscle masses to points of flexibility. 



Repeat these observations upon the ventral side. Express 

 results. 



Study these nmscle masses in the light of what has been said 

 above concerning muscle antagonism. Results? 



The Study of an Individual Muscle. For studying the fibers 

 and attachments of indiviilual nuiscles the dissecting microscope 

 may be found useful. The gastrocnemius muscle which forms 



