24 



universe, as well as economy of force. We find, therefore, that Nature 

 never uses a triangular or quadrilateral muscle except under great 

 necessity, of which I shall now give you a remarkable example (fig. 7). 



The most wonderful triangular muscle in the world is here shown in 

 the biceps femoris muscle, or the flexor of the thigh in the tiger. The 

 muscular fibres radiate from O ; they are inserted from the middle of the 

 thigh down to the heel. This enormous muscle forms one great sheet 

 of muscle passing from the tuber ischii, and spread out over a space of 

 three feet along the side of the leg. That muscle exists in me and in 

 every other mammalian animal that lives. In most other animals it is 

 arranged as a prismatic muscle. In my leg it is like a rope of parallel 

 prismatic fibres. Now, I ask — "Why has Nature deliberately sacri- 

 ficed a certain amount of force by putting a triangular muscle into the 

 leg of the tiger to do the work which she does so effectually in my leg 

 by a straight rope of muscle ?" The answer is this, that I am a man 

 and not a tiger ; I am not intended as a tiger is, to hide in a jungle, to 

 jump from the jungle at a troop of horsemen going by, to take one of 

 them and carry him off in spite of the rest, and eat him. That is not 

 the purpose for which the Creator brought me here; but if I were brought 

 here for such a purpose I am sure I should have a triangular muscle in 

 my leg. The weight of muscle to give the tiger the spring which en- 

 ables him to do these feats is so enormous, that if it were placed as a 

 single rope from point to point it would not only be a great deformity 

 in his appearance, but would seriously impede him in his progress 

 through the jungle. The clumsy nature of this enormous rope of 

 muscle attached to him would injure him, therefore Nature has de- 

 liberately thrown overboard the first idea that might present itself, 

 which was to put a great rope from point to point, and to make it 

 strong enough. "No, I cannot do that," says Nature, "I must preserve 

 beauty of form," making the tiger (what it is) the most beautiful creature 

 which God has created. Therefore, the tiger is given a triangular muscle 

 with a certain amount of loss of force, but there is a gain by spreading 

 the muscle over a great surface, a gain in the packing and shape of the 

 leg — there is more gained than lost by the apparent sacrifice of force. 



An interesting fact may here be stated, the extreme beauty of which 

 every anatomist present will appreciate. We can demonstrate, and I ask 

 you to take it for granted, that the resultant force of the fibres of quadri- 

 lateral and triangular muscles lies in the bisector of the vertical angle. 

 When I take the triangular muscle in the leg of the tiger, and draw 

 the bisector of that angle on a tiger's dead body, I find that the 

 bisector of the angle passes rigorously through the top of the fibula, 

 the peroneal or small bone of the tiger's leg, through the very spot in 

 which the biceps muscle in my leg is inserted ; so that, although the 

 tiger's muscle is triangular, it really behaves like an imaginary muscle 



