DYNAMICS IN EVOLUTION. 71 



and thus be transported forwards and poured out " anteriorly." 

 It will readily be seen that, in order to do this, work must be 

 performed, energy dissipated. This energy is dissipated in 

 reestablishing a dynamical balance between the parts of the dy- 

 namical system represented by the molecular aggregate that we 

 behold in the body of the Amceba. We have here before us a 

 finite molecular mechanism, or dynamical system, every part of 

 the surface of which returns upon itself. Any disturbance of 

 the equilibrium of the molecules at the surface of that system 

 will provoke a deformation of the whole. If the disturbance 

 is great enough at any one point, there will inevitably be 

 developed a vortex-ring motion of the particles amongst them- 

 selves, due to the friction of the constituent molecules. If 

 this vortical motion of the particles of an amoeboid mass of 

 "living" matter be due to a preponderating superficial dis- 

 turbance of the equilibrium of the system at one point on the 

 surface, that alone will suffice to determine the direction of 

 the motion of the whole. For this reason the proteus animal- 

 cule has no fixed "head" or "tail" end. "Head" and "tail" 

 seems to be entirely a matter of the combination of inner and 

 outer conditions that determine the point on the surface of the 

 organism, at which the maximum chemical and physical dis- 

 turbance of surface-tension will occur. These are absolutely 

 determined by the physical processes of the readjustment of 

 the equilibrium of its molecules, in respect to outer conditions, 

 during every consecutive moment of its motions. It is pos- 

 sible, in fact, to show that every change of the shape of this 

 interesting organism is the result of energies inter-acting in a 

 very complex way. 



If an Amoeba is allowed to fall through the water, its 

 surface-tensions are apparently disturbed with great uniformity 

 over its whole surface, and at nearly equal distances apart. 

 It results from this that short, blunt pseudopodia are pushed 

 out in every direction, as in Fig. i and it becomes nearly 

 globular in outline. The moment, however, that the organ- 

 ism touches a plane surface, as in Fig. 2, it flattens out 

 into the form of a biscuit-shaped mass. It now behaves 

 like a mass of dough, and falls into a new condition of 



