130 THE MECHANICAL FUNCTIONS. 



and consequently tense and prominent, while 

 others are relaxed and flattened ; differences 

 which it is requisite that the artist should 

 faithfully express, in order to give a correct 

 representation of the living figure. 



The dilatation of the muscular fibres in thick- 

 ness, which accompanies their contraction in 

 length, would, if these fibres had been loose 

 and unconnected, have occasioned too great a 

 separation and displacement, and have im- 

 peded their co-operation in one common effect. 

 Nature has guarded against this evil by col- 

 lecting a certain number of the elementary 

 fibrils, and tying them together with threads of 

 cellular substance ; thus forming them into a 

 larger fibre ; and again packing a number of 

 these fibres into larger bundles : always sur- 

 rounding each packet with a web of cellular 

 tissue ; which thus forms a separate investment 

 for each. This plan of successive reunion into 

 larger and larger assemblages is carried on 

 through several gradations of size, till the entire 

 muscle is completed. 



That we may be the better able to appreciate 

 the excellence of the plans adopted in the me- 

 chanism of the animal frame, let us inquire what 

 arrangements would occur to us, prior to an ac- 

 quaintance with those actually adopted, as the 

 most advantageous dispositions of the muscular 

 power. It is evident, that the simplest mode 



