PHYSIOLOGY: W. O. FENN 
535 
form. Only a few typical electrolytes are included in the diagram, but 
the general principles which they exemplify are applicable to all cases 
thus far studied. 
According to this scheme, electrolytes are found to fall into three 
groups. 
Group I includes salts with monovalent cations and monovalent 
anions, the effect of the former predominating in the presence of Group 
II, the effect of the latter in the presence of Group III. 
Group II includes alkalies and salts with bi- and trivalent anions, 
the effect of the anion predominating. 
Group III includes acids, and salts with bi- and tri-valent cations, 
the effect of the cations predominating. 
Members of any one group are additive to each other but antagonistic 
to members of either of the other two groups. In general the antagon- 
ism between Groups II and III is greater than between Groups I and II 
Group n Group I Group HI 
FIG. 1 
Aditive combinations are bracketted together. Antagonistic combinations are con- 
nected by arrows. In general, the length of the arrows indicates the amount of antagonism 
expected. 
or between Groups I and III. The valence of the ion (except H and 
OH), while not the only factor, seems of chief importance. Acids and 
alkalies are in general more effective than neutral salts. 
An exception to this rule is found in the case of MgCl2 which is found 
to antagonize both NaCl and CaCl2. This exception, however, is in 
agreement with biological results. 
As a criterion of antagonism, the precipitation of gelatine by 95% 
alcohol was used. It is found that less alcohol is required for the pre- 
cipitation of the gelatine in the presence of two antagonistic salts than when 
either is present alone. 
Let us for convenience designate the antagonistic salts as A and B. 
We find that as more and more of salt A is added to gelatine, more and 
more alcohol is required to produce an opaque precipitate, until finally 
a maximum is reached. This maximum, according to Pauli's theory,^ 
corresponds to the greatest ionization of the protein and the greatest 
viscosity. At this point the hydration of the protein is greatest and 
