INTERNAL MOVEMENTS 323 



granules overtaking one another on very minute filaments — 

 all these are phenomena which, as I believe, can be under- 

 stood much more easily on the assumption of such an 

 automatic power of movement, than on the hitherto current 

 supposition that the movement of the granules is due solely 

 to the general streaming movement of the protoplasm. 



(Z) Causes of Internal Displacements in the Alveolar 

 Protoplasm 



A further problem would be whether, on the same prin- 

 ciple, corresponding granules in the interior of the proto- 

 plasm could also carry on movements. I do not consider 

 this possibility as excluded. Since the protoplasm, ac- 

 cording to our conception, is a system of very minute 

 lamellae of fluid, in which the cavities of the meshes are 

 filled by another fluid, the enchylema, it is very possible 

 that important consequences may result in this way affecting 

 the internal movements of protoplasm. 



In such a system of fluid lamellae, as soon as the tension 

 of a lamella is altered, an influence must be exerted upon 

 the arrangement of the system. If the tension of a lamella, 

 which meets two others, in the way earlier described, at 

 angles of 120°, is raised, the lamella in question must contract 

 or shorten, so that the two lamellae will meet at an angle which 

 is less than 120°, and the resultant of their tensions now 

 maintains a state of equilibrium with the increased tension 

 of the first lamella. In the opposite case, with lowering of 

 the tension of the first lamella, there will, of course, be an 

 increase in its size and an enlargement of the angles of the 

 two others. That these theoretical assumptions can be 

 proved to be correct by means of experiment has already 

 been shown by Plateau (vol. i. pp. 368-370), who succeeded 

 in bringing about in the lamellar framework obtained by 

 dipping a wire cube into a glycerine solution of soap, both 

 contraction-like shrinkings and, on the contrary, enlarge- 

 ments of the central lamella, as the result of altering its 

 tension both by differences of temperature and by bringing 

 it upon other fluids of greater or less tension. Under 



