676 Scientific Proceedings, Royal Dublin Society. 
or permanently arranged by the action of the principle of closest- 
packing to form a homogeneous structure, and that the nature of 
the arrangement produced is such that these grouplets are found 
placed around axes of revolution of the homogeneous structure, 
i. e., 80 that each grouplet is related to the other grouplets ranged 
with it around the same axis, or point of intersection of intersecting 
axes, in a different manner from that of its relation to any of the 
other grouplets. We then see that a linking together or poly- 
merisation of the grouplets to form larger groups may occur 
wherever the arrangement is sufficiently perfect, and without destroy- 
ing homogeneity. 
Permanent combinations brought about in the way above de- 
scribed will differ in character according to the nature of the 
change of state which occurs. If the fresh linking which takes 
place is, although symmetrical, not such as to constitute a con- 
tinuous mass, it will merely produce new groups of one or more 
different kinds (polymers), which will be thrown into various 
orientations by the passing disturbances and yet strive again and 
again to recur to the closest-packed symmetrical disposition of 
which they are capable.’ If, on the other hand, the linking is con- 
tinuous, it will result in the production of a continuous solid 
homogeneous assemblage capable, under favourable conditions, of 
symmetrical growth by accretion.® ; 
And when a solid assemblage has resulted and afterwards 
experiences a change of state which liquefies it, 7. ¢., breaks it up 
into isolated units, its properties thus brought to light will depend 
on the way in which the links break—we may have sufficient 
links surviving to connect all the particles contained in a unit of 
the mass so that but one kind of group is produced,’ or we may 
have some of the links which bind the various parts of a unit 
together too weak to survive the passage out of the solid state, in 
which case two or more different kinds will be produced.® 
Again, a combination different from those just described is 
conceivable in which one of the combining constituents consists of a solid 
assemblage 1. e., of one in which the linking of the parts prevents any 
permanent alteration of their relative situations. 
’ 1 Compare p. 585. 2 Compare p. 584. 3 Compare p. 565. 
“See p. 584. Compare Min. Mag., vol. xi., p. 130. 5 Compare p. 619. 
