222 
FREDERICK BARRY 
These need not be summarized. It is sufficient if attention shall have 
been directed to the generalizations of broadest scope and most funda- 
mental implication. The laws of thermodynamics are among the few 
laws of nature which are precise beyond the limit of accurate measure- 
ment. Other generalizations are less precise because of their greater 
detail of statement, or because of simplifying assumptions deliberately 
introduced, and are to be looked upon as but first approximations 
toward the exact expression of the truth. We may even permit our- 
selves to doubt whether, in terms of formulations similar to those we 
possess, however more extensive and exact they may become, we shall 
even approach a complete analysis of physiological phenomena. 
Already, in the influence of temperature change on reaction velocity 
we have encountered a phenomenon to which our present generaliza- 
tions cannot be directly applied. It is by no means absurd to suppose 
that in colloidal system.s which never come to final equilibrium (like 
these in the living cell) the specific characters of particular regions 
within the cytoplasm — which cannot by any possibility be homo- 
geneous — will have a determinate effect on the general character of 
the cell reactions. It would be entertaining to speculate upon the 
possible connection between many physiological phenomena now little 
understood and quite possibly dependent upon this circumstance, and 
individual as contrasted with average molecular velocities. The mere 
suggestion, however, will suffice to illustrate the point ; which seems 
after all only to imply that present mechanistic conceptions will prob- 
ably need to be amplified by new considerations, to meet the needs of 
future inquiry. Our present generalizations, rough though they may 
be, are none the less of very great value, for they express the implica- 
tions of demonstrated fact ; and the history of scientific theory sustains 
the hope that in the future they will serve as a secure basis upon which 
to build the more complete formulations which, by correlating still 
wider reaches of experience, will yield us deeper insight into these 
fascinatingly perplexing problems. 
Note. — For the purpose of amplifying many of the statements and 
suggestions made in the course of this brief presentation, the following 
references may be of value. They have been selected wholly in con- 
sideration of their accessibility; and for this reason direct reference to 
original papers has not been made. Such citations, which will open 
up practically the whole literature, will be found in the works here 
listed. 
