VISCOSITY 223 



The knowledge that low concentrations of ether, chloroform, 

 etc., decrease, while higher concentrations increase protoplasmic 

 consistency, cannot but add to our understanding of anesthesia. 

 It is of interest in this connection to recall that Claude Bernard 

 regarded anesthesia as a reversible coagulation of the protoplasm 

 of the sensory nerves (page 497). Ru2i6ka advanced the 

 hypothesis (page 208) that aging is a matter of dehydration of 

 protoplasm and, therefore, of decreased colloidality and increased 

 viscosity. (In all such hypotheses, one must be careful to 

 distinguish between cause and effect.) 



H. J. Jordan has studied the bearing of viscosity changes on 

 muscular action and finds that with stimulation the colloidal 

 state of muscle (of the snail) is fully changed through the trans- 

 formation of a fluid medium into a firm body which results in 

 shortening (usually) and the production of tension. Jordan 

 adds that the physical changes in muscle are dependent upon 

 structural, elastic, and other like properties of protoplasm. 

 Probably the viscosity changes in muscle are more correctly 

 characterized as thixotropic (page 150). 



The viscosity, specific gravity, osmotic pressure, and swelling 

 of blood have been used by Ludlum and Nugent as indicative of 

 a pathological condition. Patients suffering from asthenia 

 (debility) show low values in the viscosity, etc., of their blood 

 serum, while those suffering from delirium or toxemia show 

 high values in viscosity. 



One reiteration and one caution should conclude the experi- 

 mental portion of this chapter. The reiteration is the statement 

 that protoplasmic consistency is constantly changing. Any 

 physical change {e.g., streaming, coagulation) or any chemical 

 change (e.g., rate of oxidation, digestion, synthesis) is almost 

 certain to result in a change in viscosity. Consequently — and 

 here is the caution too often neglected — it is erroneous to select 

 the only visible change, viz., one in viscosity, as the characteristic 

 effect of an external influence when viscosity may be the second- 

 ary result of any one of a number of primary changes. 



THEORY 



Viscosity vs. Plasticity. — Lucretius, two thousand years ago, 

 knew that the rheologist had some knotty problems to solve. 

 In his "Of the Nature of Things," he writes: 



