20 THE ORIGIN OF THE NERVOUS SYSTEM 
still another difficulty involved in this conception. If 
nuclear pattern is the fundamental factor in determin- 
ing cytOplasmic pattern, and if the cytoplasmic pattern 
of the egg represents the pattern determined in this 
way, as this conception apparently assumes, we should 
expect each cell which arises with a full complement of 
chromosomes from the egg gradually to approach the 
cytoplasmic pattern of the egg, even though different 
cells originally received different components of the egg 
pattern. In other words, since they all possess the same 
nuclear pattern the different cells should tend to become 
more and more alike instead of more and more different. 
But since they do become more and more different it is 
necessary to assume either that cytoplasmic pattern 
once established may continue to exist independently 
of, or in spite of nuclear pattern, or else that such 
cytOplasmic pattern may influence and alter nuclear 
pattern, and either of these assumptions amounts to an 
abandonment of the original hypothesis of nuclear 
pattern as the determining factor. In short, it is evident 
that even when we start with the cell conceived in terms 
of the theories of nuclear pattern, something more, viz., 
the action of an external factor, is necessary to account 
for the pattern of the multicellular organism. 
We may then not only reaffirm the conclusion that 
so far as the evidence goes, organismic pattern does not 
appear to be inherent in protoplasm, but we may go a 
step farther and maintain that the pattern of multicel- 
lular organisms cannot be inherent in nuclear pattern. 
Assuming that this conclusion is correct, organismic 
pattern must originate in the first instance in the 
relations between protoplasm and its environment, or 
