June, 1921] 
MACDOUGAL — WATER DEFICIT 
297 
In addition, a certain amount of lipins may be present, but as their possible 
hydration action in the colloidal mass must be very slight, they may be left 
for consideration in a discussion of other phases of protoplasmic action. 
When the general properties of these main components of living matter 
are reviewed, it is seen that the albuminous or proteinaceous substances 
are amphoteric, behaving as either acids or bases according to the hydrogen- 
ion concentration of the solution, that they generally unite with the highest 
proportion of water when in an acidified condition, and that their hydration 
is also facilitated in lesser degree by the action of bases and their salts. 
The pentosans or mucilages are weak acids and undergo the highest degree 
of hydration in neutral or slightly alkaline solutions, in extremely dilute 
solutions of the common salts of potassium, magnesium, calcium, and so- 
dium, or in the presence of certain amino-compounds described in previous 
papers. That the nitrates, chlorides, and sulphates of these metals may 
also increase the hydration capacity of the pentosans will be demonstrated 
in the present paper. 
The soaps are characterized by their capacity for forming films, and 
their high hydration capacity is altered to such degree by variations in the 
hydrogen-ion concentration of the solutions as to make them "sensitizers" 
as to acidity in any colloidal mass into which they may enter. It is to be 
noted that the range of acidity or alkalinity of interest to the physiologist 
in the present connection is that which lies between the measurements 
expressed by the symbols PH = 3 and PH = 11, and that of the salts as 
chiefly between 0.001 and 0.0001 M. 
Taking into consideration the complex conditions suggested above, it is 
reasonable to infer, since we have as yet devised no means of direct observa- 
tion, that, as the more complex proteins and the pentosans do not dissolve 
or diffuse in each other, they form separate aggregates, and that the sponge 
or meshwork of the solidified biocolloid or protoplasm must therefore consist 
of an interwoven meshwork of the two. This inference may not be carried 
safely beyond a certain point, however, nor to imply that no nitrogenous 
substances of the cell may engage, or be adsorbed by, the pentosans, since 
the results of the action of histidine, glycocoll, alanine, asparagine, and 
phenylalanine upon agar go far to suggest the possibility of such unions. The 
soaps which may be present in the cell colloids are not known to form 
combinations with the carbohydrates, and, although some uncertainty 
exists as to what disturbances may be caused by their contacts with the 
proteins, yet it may be assumed for the present that they form films en- 
closing the more solid phase of the double meshwork, being thus an inter- 
phase in the colloidal machine, highly sensitive to the action of the hydrogen- 
ion and adding greatly to the complexity of the possible action of the 
mass as a whole in response to various solutions and environmental con- 
ditions. 
In this my results are in accord with those of Dr. Clowes, who ascribes 
