represents how the length of a contracting muscle depends on the 
time. But this is not enough. The success with which Werrrasm 
SALOMONSON, HoorwreG and others have been able to represent the 
curves experimentally obtained by formulae relatively so simple, 
points to the fact that the theory, if really satisfactory, will have 
to lead to similar formulae. But in order to work out the theory so 
far, it is necessary, however to know the quantitative laws of 
swelling; to know on what it depends whether in a system of 
imbibing bodies the water will, or will not, be displaced, and 
according to what formulae the different properties of a swelling 
substance depend on the degree of imbibition. 
For pharmacodynamics. A drug absorbed in the blood, when it 
has been administered in small doses, frequently affects the funetion 
of one organ only and this is explained by assuming that a sub- 
stance causes ceteris paribus a more drastic change in the life pro- 
cesses of an organ when it is present in a greater concentration and 
by the fact that different organs absorb very different quantities of 
a drug from the same solution (blood for instance). This creates a 
connection between elective action and relative streneth of the imbibition 
in different kinds of cells '), whieh has proved fruitful as a working 
hypothesis. Of late years a commencement has been made to work out 
this theory also quantitatively. The elegant researches of W. SrravB 
on the action of veratrine on the Aplysia heart and the immuno- 
chemical theories of ARRHENIUsS may be cited as examples. In all 
these calculations. it is assumed that the so-called division rule of 
Nernst (a sequel of van ’r Horr’s laws of dilute solutions) is also 
available for the imbibition of dissolved substances in swelling bodies. 
However interesting and plausible these applications may appear, it 
admits in my opinion of serious doubt whether in all these cases 
the laws of dilute solutions have been used within their proper 
limits.*) If they have not, the argument would, in some cases, not 
rest on a sufficiently firm basis, notwithstanding its apparent solidity. 
This difficult question can oniy be answered when a thorough 
knowledge of quantitative laws and an explanation of the swelling 
process is obtained. 
Hor preparative physiological chemistry. All polysaccharides and 
albuminous substances undergo swelling in water and it is greatly 
in consequence of this property that the chemistry of these substances 
‘) Compare H. J. Hamruraer, De physische scheikunde en hare beteekenis voor 
de geneeskundige wetenschappen, 1901, pag. 7, 20. 
2) | will refer to this important question in detail, later. 
63* 
