EPIGENESIS OR EVOLUTION. 125 



hands admitted to exhibit vital phenomena, they themselves 

 have functions, for that is what is meant by saying that 

 they are bearers of heredity, that they are capable of 

 assimilation, growth, multiplication. If function presupposes 

 structure, the units themselves must have their structural 

 characters to account for their functions, they must them- 

 selves be compounded of further units, and so on ad infini- 

 tum. The form standpoint, the morphological conception, 

 involves a new doctrine of emboitement. It may be an- 

 swered that the molecular constitution of the form elements 

 is sufficient to account for their functions, but, if so, why 

 may not molecular constitution suffice for the explanation of 

 the functions, even for the observed structure of cells? Is 

 it really necessary to carry structural analysis beyond the 

 point which we can recognise with our microscopes ? We 

 may concede a great complexity of molecular structure to 

 the idioplasm of the nucleus without admitting the existence 

 of structure or organisation in its proper sense. May we 

 not make some use of "polarity"? The molecules in a 

 solution may arrange themselves in definite manner and 

 form crystals, but we do not say on this account that the 

 molecules in the solution are arranged in definite form ele- 

 ments, as crystal determinants. On the contrary, the form 

 assumed by the molecules is attributed to certain attractions 

 and repulsions, but what the essence of those attractions 

 or repulsions may be it passes the wit of man to conceive. 

 At any rate it is not supposed that these inorganic forces 

 must have bodies to dwell in, and the so-called axiom, that 

 function presupposes form, appears to me to be nothing 

 more than a most unphilosophical postulate, that organic 

 forces (whatever they may be)"must have bodies to dwell in. 

 The issue between an epigenetic and an evolutionary 

 theory to account for the phenomena of development is 

 narrowed down to this : Must structure and definite organ- 

 isation be predicated of everything that manifests vital 

 activity ? Until very recent years the answer has been 

 unhesitatingly no, and an epigenetic explanation of develop- 

 ment has consequently been conceivable, though it has never 

 been satisfactorily formulated. If, contrariwise, the answer 



