1 6 A. W. GREELEV. 



particles are widely scattered. After a residence in these solu- 

 tions of ten to fifteen minutes, no vestige of the paramoecia 

 remains beyond the scattered protoplasmic granules. 



The above experiments were repeated on Vorticclla, Stcntor 

 and Hydra, and essentially the same structural changes were 

 produced. The protoplasm of Vorticella reacts to electrolytes 

 exactly as does the protoplasm of Paramoscium. In Stcntor the 

 differentiation between the two layers of protoplasm, endosarc 

 andectosarc, is more complete, and tl*e less differentiated granular 

 endosarc responds to the solutions in the typical manner, while the 

 clear striated ectosarc remains practically unaffected. Thus the 

 process of coagulation results in the formation of a cell whose 

 endosarc is shrunken into a dense, spherical mass within the 

 ectosarc, which retains its original form and size. During lique- 

 faction the endosarc becomes wholly transparent, and we have pro- 

 duced an apparently empty cell which is bounded by the un- 

 changed ectosarc as before. Hydra reacts in the same manner, 

 the endoderm responding to the solutions as did the endosarc of 

 Stentor ; and we have produced animals of the original size and 

 shape, but with either a coagulated or liquefied interior. It appears 

 from these experiments that the physical conditions already de- 

 scribed are applicable to protoplasm only in its primitive granular 

 condition. The differentiation into such simple structures as the 

 ectosarc of Stcntor, or the ectoderm of Hydra has changed to 

 some extent its elementary physical state. The high degree of 

 viscosity of such protoplasm suggests that it is normally much 

 nearer the " gel " phase. 



Like all the typical physical modifications of protoplasm, these 

 changes of structure are reversible, if they are stopped at the 

 proper time. Thus coagulated protoplasm may be again lique- 

 fied by the action of a powerful anion, or liquefied protoplasm 

 may be coagulated by a cathion. This fact seems to show with 

 special force that the physical state of the protoplasm at any 

 moment is the result of a definite reaction to the chemical condi- 

 tions of the environment. 



The whole behavior of protoplasm under the action of dilute 

 solutions of electrolytes suggests the conclusion, that, as far as its 

 chemical and physical reactions are concerned, it is a colloidal 



