ORGAN AND FUNCTION. 



77 



We might multiply indefinitely examples which prove the 

 perfect harmony between the form of the muscles and the 

 characters of their functions. Everywhere the transverse 

 development of these organs is associated with strength, as 

 in the triceps of the kangaroo, or the masseters of the lion • 



Fig. 17. — Muscle of the thigh in the Magot ; rectus internus muscle almost 

 entirely formed of red fibres ; the attachments of this muscle being at 

 a considerable distance from the knee, give it a great extent of move- 

 ment in bending the leg upon the thigh. Sartorius muscle, having a very 

 short tendon. 



everywhere also, the length of muscle is connected with the 

 extent of movement, as in the examples which we have just 

 cited. 



Is this harmony pre-established, or rather is it formed under 

 the influence of function in different creatures ? In the same 

 manner as we see the muscles increase in volume by the 

 habit of employing energetic efforts ; we also observe them, 



