THE THEORETICAL RESPONSE OF LIVING CELLS TO CON- 

 TACT WITH SOLID BODIES. 



By WALLACE O. FENN. 



{From the Laboratory of Applied Physiology, Harvard Medical School, Boston.) 



(Received for publication, December 23, 1921.) 



Recent discussions of the behavior of living cells in contact with 

 solid bodies have been published by Loeb (1) and Tait (2). Both 

 authors admit that two factors are involved in the reactions of the 

 cells — changes in consistency of the protoplasm and surface tension 

 forces. Tait lays particular stress on the latter, while Loeb believes 

 that changes in consistency are more important. The latter has, 

 perhaps, taken a somewhat safer position in his interpretation of the 

 phenomena described. It would seem, however, that the relative 

 importance of these two factors must vary with the particular type 

 of cell chosen and the conditions of observation. Thus, invertebrate 

 blood cells are more at the mercy of surface tension forces on coming 

 into contact with a soUd body than Amoeha or mammalian leucocytes. 

 It is certainly true, nevertheless, that all blood cells are subjected to 

 the abnormal forces of surface tension when they strike a foreign body. 

 Whether or not these forces are sufficient to determine the behavior 

 of the cell depends upon its fluidity. If it is only to enable us to dis- 

 cuss intelligently the relative importance of consistency changes and 

 surface tension forces as applied to cells, it is necessary to formulate 

 these hypotheses as accurately as possible. 



There is, unfortunately, little to be said about such an indefinite 

 factor as changes in the consistency of protoplasm, but surface ten- 

 sion lends itself readily to quantitative treatment. Tait has en- 

 deavored to predict the behavior of cells in contact with flat surfaces 

 and small solid bodies from principles of surface tension. His dis- 

 cussion, however, was both incomplete and, in respect to phagocytosis 

 of small bodies, erroneous. It seems important, therefore, to am- 

 plify and correct his discussion of the theory. 



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