56 DYNAMICS OF LIVING MATTER 



the moving oil will, through friction, set the adjoining particles of water 

 also in motion. The superficial layers of water, therefore, will move 

 away from the center of spreading, and water will move toward the 



center from the interior, and 

 from below. The arrows in. 

 Fig. 8 represent the currents 

 in the water caused by the 

 spreading of the oil. 



Quincke holds that such 

 pjj, g phenomena of spreading are 



the cause of all protoplasmic 

 streaming. Such a streaming occurs constantly in the cells of Chara 

 or Nitella. Quincke gives the following explanation for this process : 

 all protoplasm contains oil or fat, and the surface layer of each cell 

 must, therefore, be surrounded by a film of oil or fat. The oil will 

 form through hydrolysis traces of fatty acid. The protoplasm contains 

 substances which form soaps with the fatty acid. A soap solution 

 must spread at the hmit between oil and water, as the surface tension 

 between oil and water is greater than the sums of surface tension 

 between oil and soap solution, and between water and soap solution 

 (which is zero). When the soap solution spreads, it must pull with it 

 the adjacent particles of protoplasm. In this phenomenon of spreading, 

 new particles of the surface of oil come in contact with protoplasm, 

 new soap is formed, and the process is repeated. These phenomena 

 of spreading, which constantly repeat themselves, furnish the energy 

 for the constant streaming of protoplasm. The protoplasmic streaming 

 occurs in the case of Chara or Nitella in one direction only. Quincke 

 believes that this is due to an asymmetry in the structure of the cell, 

 which renders the resistance to the streaming greater in one direction 

 than in the opposite direction. Hence, the streaming occurs in one 

 direction only; namely, that of least resistance. 



The motion of an Amoeba can be imitated by bringing a drop of 

 olive oil which contains a trace of fatty acid upon a one half to two 

 per cent solution of Na^COj. The oil, in this case, forms at its surface a 

 film of sohd soap. As soon as this dissolves at one spot, soap solution 

 must spread at the surface of water and oil, and the moving soap solution 

 must set also the neighboring layer of oil into motion. In the oil drop, 

 therefore, two movements must occur, one at the periphery, which is 

 directed away from, and one in the center, which is directed toward, 

 the center of spreading. The arrows in Fig. 9 indicate these streams. 

 The particles that flow from the interior toward the periphery produce 

 a bulging out, and this is the analogue of the formation of a pseudo- 



