254 THEORETICAL BIOLOGY 



rules ; for the rule of genesis controls the impulses in the 

 embryo, and the rule of function those in the full-grown 

 organism. 



I have already pointed out the relations between rule of 

 genesis and rule of function, and I have shown that in the 

 amoebae both rules together control the formation of the 

 pseudopodia. In animals with a framework, on the contrary, 

 the rule of genesis holds sway only during the first portion of 

 the hfe. 



Now Roux, the pioneer founder of experimental 

 embryology, showed that the goal (namely the finished 

 framework capable of functioning) is more certain than the 

 route followed (i.e. the normal course of development). From 

 this we may deduce an influence of the function-rule on the 

 rule of genesis, an influence not yet investigated. 



If we find it difficult to admit the influence of the one 

 rule on the other, let us remember that, in their very nature, 

 the rules are active factors, and so may also be called re- 

 gulators. Now the analogies for these regulators are to be 

 sought, not in the domain of mechanics, but in that of music. 

 And so we may say that the melody of function influences 

 the melody of genesis. 



It is very difficult to visualise even this much in the 

 required degree ; and in considering the origin of species 

 and community it is at first utterly confusing, since we have 

 to keep before our eyes the influence of three melodies on 

 the melody of genesis. The melody of function, the melody 

 of the species and the melody of the community come to 

 expression in the arrangement and seriation of the polar 

 systems of impulses. The individual organism formed 

 during development in such a way that it becomes a struc- 

 ture capable of functioning, becomes at the same time a 

 member of the community, and, by the mere fact of its exist- 

 ence, forms a part cJ the species. 



