SURFACE TENSION HYPOTHESES 



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(i) Hypotheses relating to Surface Tension Berthold, 

 Quincke 



It has already been occasionally pointed out here and 

 there, that in bringing about protoplasmic movements the 

 phenomena of the so-called surface tension of the fluids may 

 play a part. 



Hofmeister attempted, as far back as 1867, to interpret 

 the so-called rounding off of drops of protoplasm, which 

 has often been regarded as a phenomenon of contraction, 

 as a property identical with the tendency to assume a 

 spherical form in ordinary drops of fluid, that is to say, as 

 an effect of the surface tension. 



Engelmann also, on the ground of his idea that proto- 

 plasm becomes fluid by electrical stimulation, arrived (1869) 

 at the view that the forces which cause the contraction of 

 protoplasm "may be just the same as those which tend 

 to make every non- spherical free drop of fluid become 

 spherical " ; that would, of course, be the surface tension. 

 He is, with Hofmeister, completely convinced of the fact 

 that contractions, in the ordinary sense, are not the cause of 

 movements, and agrees entirely with the view of the latter 

 oncerning the extension of the currents backwards. At 

 later date, however, Engelmann did not recur again 

 > this, in my opinion, very correct idea, but developed, as 

 e have seen, a theory of movement based on essentially 

 ;her grounds. 



In 1876 I tried to make use of surface tension 

 ypothetically as the efficient cause in the explanation of 

 ill division. As I have already remarked, I regard the 

 xplanation given then as still suitable in its main points, 

 ud indeed as having become considerably more probable 

 rom recent observations with regard to the great part played 

 y surface tension as an important cause of the processes 

 f movement in protoplasm. Since the time when I first 

 rrived at the conviction that this property of fluid bodies 

 lust be of pre-eminent importance for the explanation of 

 be changes in form exhibited by fluid protoplasm, I have 



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