Anatomy of Fibula. 367 



So when one comes to the question of which of the two lines 

 is the correct one to follow one must decide for the latter — or 

 deny the doctrine of evolution, and ignore the results of com- 

 parative anatomy. 



It is a decision arrived at on philosophical grounds, and 

 without appeal to the question of expediency, involved in the 

 deficient vitality, and hence of energy of repair in the atro- 

 phying parts, upon which one depends for union in the plastic 

 operation — apart fromi the difficulty of obtaining suitable 

 human bone Avith which to make the attempt. 



Recognising the lesson as previously stated that bone is 

 dominated by muscle, it is scarcely understandable that ana- 

 tomists should pay so much attention to the minute description 

 of bones, and yet such little regard — as evidenced in any 

 anatomical text book — to the important factor of muscular 

 action, on which the bony changes depend, and Avhich the 

 science of evolution shows us existed before bone had its being. 



I beg to thank Dr. Stapley for valued assistance, and the use 

 of material — ^Mr. Lewis, B.V.S., Research Scholar, lor the photo- 

 graphs, and Mr. Thwaites, M.Sc., for help in the preparations 

 of the dissections, and for some physiological considerations of 

 the functions of the parts concerned. 



EXPLANATION OF PLATES LXXVI.-LXXVIII. 



Plate LXXVL 



Fig. 1. — Tibia and fibula of Koala (Phascolarctus cinereus). 

 ,, 2. — ,, of Lace lizard or Monitor (Varanus varius). 



Plate LXXVII. 



Fig. 3. — Tibia and fibula of Kangaroo. 

 ,, 4.— ,, of Sheep. 



Platk lxxvui. 



Fig. 5. — Tibia and fibula of Opossum (Tiicliosurus). 

 ,, 6. — ,, of Agouti (Dasyprocba). 

 „ 7. — ,, of Hare (Lepus). 

 „ 8. — ,, of Echidna (Tachyglossus aculeatus). 

 ,, 9. — „ of Wombat (Phascolomys sp.). 



