IV. VISCOSITY MEASUREMENTS 129 



important int'ijrniation. As yet, tlierc lui\-e been no iiecunite studies 

 of nerve cells, but conceivably the centrifuge method can be used on 

 the giant nerve cells of annelids. In the past the only animal cells 

 that have given results that have been useful were marine egg cells 

 and protozoan cells. The egg cells can be studietl only at marine 

 laboratories and then only at certain seasons of the yeai". Protozoan 

 cells are often difficult to handle. If a careful search is made, it 

 should be possible to discover new types of material for measurements 

 of protoplasmic viscosity. If this material can be found, the future 

 for the field would be very bright indeed. The colloidal behavior of 

 protoplasm is best studied by viscositj^ measiu'ements. If we knew 

 more about the colloid chemistry of protoplasm, we would be in a 

 position to provide basic information useful not only for the biologist 

 and phj^siologist, but also for the pathologist, the pharmacologist, 

 and even for the clinician. For surely knowledge as to the nature and 

 behavior of the protoplasmic colloid is of primary importance for all 

 sciences concerned with the behavior of living organisms. 



References 



1 . Heilbrunn, L. V., The Colloid Chemistry of Protoplasm. Borntraeger, 



Berlin, 1928. 



2. Heilbrunn, L. V., and F. J. Wiercinski, /. Cellular Camp. Physiol., 29, 



15 (1947). 

 S. Barr, G., A Monograph of Viscometry. Oxford Univ. Press, London, 1931. 



4. Bingham, E., Fluidity and Plasticity. McGraw-Hill, New York. 1922. 



5. Hatschek, E., The Viscosity of Liquids. Bell, London, 1928. 



6. Scott Blair, G. W., Ayi Introduction to Industrial Rheology, Blakiston, 



Philadelphia, 1938; A Survey of General and Applied Rheology, Pit- 

 man, London, 1943. 



7. Reiner, ^NI., Ten Lectures r'n Theoretical Rheology. ]\Lass, Jerusalem. 



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8. Tobolsky, A., R. E. Powell, and H. Eyring, "Elastic-Viscous Properties 



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