70 ANIMAL MKCHAMSM. 



cm contract. I!ut, \\hatevrr may be tlic absolute value of 

 this contraction, it is always in proportion to the length of 

 red film- , that is the result of the nature of the phenomena 

 which prodiN work in the muscle. 



Thus, every muscle whose two points of attachment are 

 Misceptil'lc of being much displaced by the effect of contrac- 

 tion, mn>t nei -es>arily be a long muscle. Oil the contrary, 

 every muscle which lias to produce a movement of short 

 extent must of necessity be a short muscle, whatever may bo 

 the distance which separates the two points of attachment. 

 Thus, the ili-xors of the fingers and toes are short muscles; 

 but they are furnished with long tendons, which convey even 

 to the phalanges of the ringers or toes the slight movement 

 originated at a considerable distance at the fore-arm or the leg. 



It is easy to estimate, in the dead body, the extent of the 

 displacement which a muscle can exercise on its two points of 

 attachment. By producing the movements of flexion or 

 extension in a limb, we can ascertain with sufficient exact- 

 ness the extent by which they separate or draw together the 

 osseous attachments of its muscles. In a recent skeleton we 

 can also judge with sufficient accuracy of the amount of these 

 movements by the extent to which the articulated surfaces 

 can glide over each other. 



In examining the muscular frame of man we are struck 

 w ith the extreme length of the sartorius muscle ; it is easy 

 to be seen that no other can displace to such an extent its 

 ] "ints of bony attachment. The sterno-mastoidal and the 

 HHI/IHUS rectus iibdoininis are, after this, the longest muscles ; 

 thcM- also are muscles which have very extensive movements. 

 "We might thus cause all the muscles of the organism to pass 

 under review, and in them all we should see that the length 

 of the red fibres corresponds with the extent of the movement 

 which this muscle has to execute. But, in the study, we 

 must be on our guard against a cause of error which would 

 t n<l to arrange certain short muscles among those which are 

 Long 



l;<>ivlli himself has noticed this cause ot error; ho lias 

 i-houn how jH-iiiiij'iinn muscles, that is to say, those whose 

 lil'M - .!! m-i iteil obliquely into the tendon, like the barbs of 



