28 THE EQUILIBRIUM OF COLLOID AND 



The whole of the experiments lend support to the view that 

 the living cell exists in a periodically or phasically varying osmotic 

 equilibrium with its surroundings, and not in a state of osmotic 

 equality with them. The cell by its unions with crystalloids pre- 

 serves a distinct osmotic condition within its bounds different 

 from that in the surrounding fluid media from which its nutrient 

 materials are taken up. This is particularly well seen when the 

 medium without is subject to considerable and accidental varia- 

 tions. Even in those cases where the outer medium is practically 

 constant, as in the extreme case, for example, of blood corpuscle 

 and plasma, although there appears to be an existence of osmotic- 

 equality within the cell, and without, yet this is due to the peculiar 

 conditions having induced a close coincidence of the two sets of 

 osmotic phenomena, and the existence of an equilibrium and not 

 an equality may be easily shown by suitably varying the condi- 

 tions. So that even in these extreme cases what we have to do 

 with is not really equality of osmotic pressures, but an equilibrium 

 which happens to simulate equality from the presence of reducing 

 conditions ; the equality disappears as soon as these reducing 

 conditions are disturbed. 



When the corpuscles of whipped blood are separated as com- 

 pletely as possible from the serum by means of the centrifuge, 

 and the depressions of freezing point of the corpuscles and of 

 the serum separately determined, it is found that the freezing 

 point of the serum lies on the average at O02 to O03 C. lower 

 than that of the corpuscles. This difference, small as it is, is con- 

 stant in its occurrence, and corresponds to a difference in osmotic 

 pressure of approximately 200 to 300 m.m. of mercury. If the 

 corpuscles after separation from the serum are thoroughly shaken 

 up with saline solutions weaker and stronger than the serum, or 

 as they are termed, hypo- and hyper-tonic solutions, it is always 

 found, on again separating corpuscles and saline by means of the 

 centrifuge, that the depression of the freezing point of the saline 

 is greater than that of the corpuscles, no matter whether the saline 

 employed was hypotonic or hypertonic. The differences become 

 in these cases much greater than the natural differences between 

 corpuscles and serum. These results show that there is established, 

 as the concentration of the saline is varied, an equilibrium for 

 each strength of saline, but not an equality, there always being a 

 negative osmotic difference within the corpuscle. 



