302 Explanation of Inheritance 
hypothesis is able to explain particulate inheritance com- 
pletely, without requiring the help of any preformistic 
germs whatever. Concretely: let us imagine two exactly 
similar phonographs, and let us have the same singer 
render the same melody in exactly the same way first 
before one then before the other. Only let us suppose 
that one hears at a certain moment during the second 
song, for example, one of the audience cough, or a door 
slam, or clapping of applause. Obviously both phono- 
graphs now will reproduce the same melody in the same 
way, with the single difference of the accessory noise, 
which will not destroy in the slightest the otherwise com- 
plete conformity of the two phonographic reproductions. 
Thus we have here an actual and characteristic case of 
particulate inheritance for the production of which it is 
mechanically sufficient that the series of successive specific 
vibrations of the middle point of the membrane differs 
from the corresponding series of vibrations in the other 
phonograph only through a single vibration or through 
a very inconsiderable group of these specific vibrations. 
From the explanation which centroepigenesis gives of 
the inheritance of acquired characters there follows also 
at once a very important consequence. If we mean by 
functional stimulus not so much the external influence as 
rather the immediate modification induced by it in the 
vital process, then the functional stimulus according to 
the centroepigenetic hypothesis is of quite the same 
nature as the ontogenetic stimulus. And this appears to 
be indicated also by the best demonstrated facts. 
We regard it as absolutely necessary to understand 
first clearly this distinction between external physical 
actions and functional stimulus. For the former do not 
themselves constitute the true and proper functional 
