Physical Asjiects of Protoplasmic Streaming 209 



possibility of causing protoplasm to flow under various rates of 

 shear. It may be that the capillary method will help throw some 

 light on the study of the anomalous, or non-Newtonian, flow of 

 protoplasm which is at the present time based upon a complex 

 mixture of fact and theory. 

 Motive Force versus Viscosity. 



* As remarked by Ewart (1903, 61) , the speed of the flow is 

 dependent upon viscosity as well as upon the motive force which 

 drives the protoplasm. In fact, streaming must be considered in 

 terms of these two variables. There has been, however, no method 

 developed to measure the motive force, which is a fundamental factor 

 in the mechanics of protoplasmic flow. Heilbrunn (1937, 243) pointed 

 out the difficulty arising from an attempt to interpret the result 

 of experiments on protoplasmic streaming, since it was impossible 

 to decide to what extent a change in speed is due to a modification 

 of the motive force, and to what extent it is due to a change in the 

 viscosity of the protoplasm. It is hoped that the experiments reported 

 above may make some contribution to analytical studies on the effect 

 of physical and chemical agents on protoplasmic streaming. Some 

 of the observations made that might prove to be of value in this 

 respect, are as follows: ascertaining, when an external agent has been 

 applied that the protoplasmic flow is stopped because of an immense 

 increase in viscosity rather than a dying away of the motive force; 

 or ascertaining that the situation is different, namely, the flow is 

 retarded because of a reduction in motive force rather than an 

 increase of the viscosity. 



VI. GRAPHICAL REPRESENTATION OF THE MOTIVE FORCE— 

 "DYNAMOPLASMOGRAM" 



In section IV, it was stated that the balance-pressure must be 

 adjusted continuously in order to keep the protoplasm quiet. Since 

 the balance-pressure is a measure of the motive force, an increase 

 and decrease of it must mean a parallel change in the motive force. 

 Changes in the balance-pressure reveal autonomic variations of the 

 mechanical forces liberated in the vital system. 



In order to determine in what manner and to what extent the 

 motive force changes in relation to time, instantaneous values of the 

 balance-pressure were read at 5-second intervals. The recording 

 was made by another observer, who watched the manometer.- The 



' I am indebted to Miss A. Cantlin, Mr. J. Evans, Mr. R. Ferlauto, Mr. M. Ross, 

 Miss M. Uraguchi and others for their kind assistance in the experiment. 



