Further Tests of the Elasticity of Protoplasm

It is possible to produce changes in fluidity of protoplasts by means of the varying shearing stresses to which they are subjected. In consequence of the different fluidity of the objects, the speed of their deformation is dependent upon the pressure or shearing stress used. In further experiments the relative effects of changes of temperature and of different concentrations of anisotonic media were studied, and in supplementary experiments with inanimate model drops, it was verified that the phenomenon of increasing ``apparent fluidity'' depending on the shearing stress is probably due to the structure causing elasticity. Not only the plasmalemma, but also the interior of the protoplasts is more fluid as the shearing stress increases, for the Brownian movement of particles of the inner layer is more rapid. From these experimentally determined facts the conclusion is drawn that the tangential expansion for protoplasm, as of any non‐Newtonian fluid, is a function of the tangential shear γ and its change in time: $$\mathrm{\tau =f(\gamma ·d\gamma /dt).}$$