82 LIBBIE H. HYMAN 



indicating the greater thickness of the surface gel in the former 

 case. This I also have found to be true. I have frequently 

 performed the following experiment on amoeba. The tips of the 

 pseudopodia of the hay amoeba cling so firmly to the substra- 

 tum that if a needle is applied to the posterior end and a pull 

 exerted, the animals can often be pulled in two. In such cases 

 the ectoplasm is stretched and drawn out into strands, a behavior 

 that leaves no- doubt that it is of a firm consistence and yet 

 extensile. 



Jennings ('04) records a great number of interesting observa- 

 tions that demonstrate the firm and contractile nature of the 

 ectoplasm. For instance, in the retraction of pseudopodia 

 either as a result of stimulation or in the course of locomotion, the 

 surface of the pseudopodium is thrown into folds and corrugations. 

 The posterior end is likewise always corrugated. I can fully con- 

 firm Jennings in these statements. This behavior necessitates 

 the assumption, as Rhumbler ('05) recognizes, that the surface is 

 heterogeneously solidified. Jennings also finds that the ecto- 

 plasm possesses elasticity and contractility, properties which 

 again indicate its more or less solid character. The pseudopodia 

 can be bent, as can the entire body, and both return to their 

 original position, a property of solids, not of fluids. The ecto- 

 plasm acts like a Hough skin.' When a contracted pseudopo- 

 dium, composed of ectoplasm alone again comes into action, as 

 often happens, the returning endoplasm straightens it out "with 

 a sort of jerk," as if it were an empty wrinkled glove finger. I 

 have frequently made the same observations. Dellinger ('06) 

 observes that amoebae may be rolled about with a needle; they 

 not only retain their form under such treatment but the endo- 

 plasmic granules do not shift their positions. This again in- 

 dicates a degree of firmness and solidity of the ectoplasm which 

 is incompatible with the surface tension theory, and shows also 

 that the endoplasm is not very fluid, or at least that it may become 

 fairly rigid. 



It seems unnecessary to recount here any further observational 

 details which demonstrate the non-fluidity of the ectoplasm. I 

 have made a great many such observations myself but found 



