366 NATURE'S TEACHINGS. 



sundry layers of sinew which have been affixed to the back 

 when wet, and which add enormously to the power of the bow, 

 while they very little enlarge its dimensions. 



Another bow, made by the natives of Vancouver's Island, has 

 the back strengthened by a number of cords spun from sinew 

 fibres, and possessing the strength and elasticity to which we 

 are accustomed in the strings of the harp, guitar, or violin. 



will now turn to a parallel in Nature. This is to be 

 found in the lower jaw of the Crocodile, as is pointed out by 

 Professor Owen, in his work on the " Skeleton and the Teeth." 



All persons who have a smattering of anatomy are aware 

 that even in the human body the most solid bones of the adult 

 were originally composed of several pieces, and that they only 

 become fused together in course of time. The jaw-bones, for 

 example, were once so composed, and in the Crocodile the 

 junction is never completed, the pieces of bone remaining 

 separate, but being pressed firmly against each other during 

 life. 



I have now before me the skull of a Gangetic Crocodile, in 

 which, although the animal was an adult when killed, the 

 bones of the long lower jaw are so loose that unless they were 

 tied together the jaw would fall to pieces. 



This analogy between Art and Nature is thus described by 

 Professor Owen in the work which has just been mentioned :- 



" The purpose of this subdivision of the lower jaw-bone has 

 been well explained by Conybeare and Buckland, by the 

 analogy of its structure to that adopted in binding together 

 several parallel plates of elastic wood or steel to make a cross- 

 bow, and also in setting together thin plates of steel in the 

 carriage spring." 



Dr. Buckland also adds: "Those who have witnessed the 

 shock given to the head of a Crocodile by the act of snapping 

 together its thin, long jaws, must have seen how liable to 

 fracture the lower jaw would be were it composed of one bone 

 only ..... The splicing and bracing together of thin flat 

 bones of unequal length and of varying thickness afford com- 

 pensation for the weakness and risk of fracture that would 

 otherwise have attended the elongation of the parts." 



A good example of the value of this structure of bone may 



