CERTAIN ASPECTS OF THE PROBLEM OF 
PHYSIOLOGICAL CORRELATION^ 
C. M. Child 
(Received for publication January 14, 1921) 
The existence in the growth and development of axiate plants of a 
relation of dominance and subordination, of control and being controlled, 
has long been recognized. This relation is very evidently associated in 
some way with at least certain fundamental physiological activities of plant 
protoplasm and apparently particularly those which have to do with 
growth. The active vegetative tips are the chief regions of dominance, 
but other growing regions may exercise a similar dominance to a greater or 
less degree. That this relation is a real physiological relation and dependent 
on the dynamic activity of the dominant part has been demonstrated 
repeatedly by experiments in which the dominance is abolished by inhibition 
of the fundamental metabolism and growth of the dominant region, but 
reappears when the inhibiting factor is removed and the dominant region 
returns to or approaches its original condition. 
My work on so-called physiological polarity, correlation, and integration 
in animals has shown very clearly that in axiate animals as well as in plants 
a relation of dominance and subordination exists, not only as regards the 
functional activities of the fully developed individual, but also in growth 
and development. The evidence indicates that the functional relations of 
later stages as expressed in the nervous system and in the chemical inter- 
relation of parts are the consequence and outgrowth of a more general 
and primitive relation which exists before the nervous system appears and 
before the various parts differentiate. Since this relation in its more 
general form as it appears in the simpler animals and the earlier stages of 
development seems to be very similar to the relation in plants, I have very 
naturally been much interested in attempting by means of work along 
various lines with plants to discover whether, or to what extent, such simi- 
larity exists. It is because of some of this work on plants that I have been 
asked to take part in this program. My objection that the work cannot 
properly be regarded as biophysics any more than biochemics, and that it has 
not yet attained the exact quantitative character and formulation which 
would warrant its inclusion in either of these special fields of physiology, 
was overruled by those in charge of the program, so that responsibility 
rests upon them. 
1 Invitation paper read before the Physiological Section of the Botanical Society of 
America, in the sympDsium on biophysics, at Chicago, December 28, 1920. 
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