SOME PHYSICAL PROPERTIES OF PROTOPLASM 

 AND THEIR BEARING ON STRUCTURE 



William Seifriz 



The demonstrable physical properties of protoplasm indicate its 

 hidden structure. In the introduction to this Monograph, I dealt 

 with bonds between linear molecules. Neither the bonds nor the 

 linear molecules which they tie together is visible, but their pres- 

 ence is required to satisfy the needs of a fluid and elastic system. 



There are many qualities of living matter which owe their 

 existence to specific structural features. One of these is thixotropic 

 behavior. 



THIXOTROPY 



Professor Freundlich, in his contribution to this Monograph, has 

 discussed thixotropy from a purely physical and chemical point of 

 view. He would have added some biological applications had he 

 lived to complete the chapter. I shall, therefore, do this for him, 

 and then tell in more detail of one application to which I have of 

 late devoted considerable attention. 



Thixotropy, as originally described by Schalek and Szegvary^, 

 referred to the sudden collapse of a gel due to mechanical agitation. 

 A simple example of this in living matter is the commonly observed 

 liquefaction of protoplasm when disturbed by a needle. Mechanical 

 agitation is, however, just as likely to produce solidification of proto- 

 plasm as liquefaction, for the most common characteristic of death 

 is coagulation. I shall later suggest that both phenomena, when 

 they occur suddenly, may be included under the term thixotropic 

 behavior. 



More closely resembling the original observation of Schalek and 

 Szegvary is the complete and sudden collapse of one-celled organ- 

 isms when severely punctured by a needle. Protozoa and the eggs 

 of algae often disintegrate instantaneously on being quickly punc- 

 tured with a needle; they literally blow up. Very striking also is 

 the complete collapse of a dividing echinoderm egg in midmitosis 



'Kolloid Zeitschr., 32, 318: 33, 326. 1923. 



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