
290 THE EVOLUTION OF LIFE 
cases there is a similarity of product, because the crystalline or 
organic form produced is to be regarded as the physical expression 
of the harmonious actions which have led to its production— 
because the forms are the results of a physical necessity, and not 
of a mere blind chance.” 
Recent observations have indeed shown that the 
absolute constancy in regard to the form of crystals 
is far more strict than was previously supposed. 
Thus A. E. H. Tutton in an interesting article on 
“The Study of Crystals” says:! “One of the 
main results of recent investigation has been to 
prove that the beautiful exterior shapes of crystals, 
as defined by the geometrical angles between the 
numerous truly plane natural facets, rather than by 
the relative development of those planes, is an in- 
variable and characteristic property of the substance 
composing the crystal, by which that substance can 
be identified from all the countless other substances 
which are known to exist.” Moreover, he adds, 
“the refractive power and the behaviour of the 
crystal in polarised light afford immediate evidence 
of identity almost as valuable as the angles between 
the natural facets.” 
The constancy of these properties in crystals in 
accordance with their molecular composition and 
structure is an interesting fact, when we consider 
that crystals are always born anew—that heredity 
has nothing whatever to do with their properties. 
Similarly, I would say that the Bacteria and Torulze 
that are ever being born anew can owe nothing to 
heredity, but that their shapes and properties must 
1 The Times, Engineering Supplement, Sep. 19, 1906, p. 298 
