VII] OF SHRINKAGE-PATTERNS 565 



way nodes*. Nature will ring the changes on the resultant patterns, 

 according as the surface be plane or curved, spherical or cylindrical, 

 coarse or fine, fragile or tough. But on these general fines very 

 many structures, both regular and irregular, spines, bristles, ridges, 

 tubercles and wrinkled patterns, bid fair to find their physical or 

 mechanical interpretation; and it is in the more or less hardened 

 parts of plant or animal that we find them one and all displayed. 

 On the egg of a butterfly, on the grooved and dotted elytron of a 

 beetle, on the notched forehead of a scarab, in thesaw-fike teeth on 

 a grasshopper's leg, in the little fines of dotted tubercles on the 

 shell of a Rissoa, more crudely in the lozenged bark of elm or pine, 

 we see a very few of this innumerable class of " shrinkage-patterns." 



* The fact that such triplets of divergent ridges or crests are not a feature in 

 the topography of mountain-ranges is a strong argument against the view that 

 general shrinkage accounts for the pattern of the earth's crust. Cf. A. J. Bull, 

 The pattern of a contracting earth, Geolog. Mag. lxix, pp. 73-75, 1932; A. E. B. 

 de Chancourtois, <^.R. lix, p. 348, 1903. 



