CHAPTER VII 

 EXPERIMENTS ON THE SURFACE LAYER OF THE AMEBA 



In the preceding chapters we have discussed the streaming of 

 the endoplasm in various representative species of ameba, and 

 its transformation into ectoplasm at the anterior end. We have 

 observed that the details of streaming are not quite the same for 

 any two species of ameba, and that in consequence the character 

 of locomotion also is specific for every ameba. All the obser- 

 vations prove that movement in ameba is always associated with 

 streaming, and streaming (in locomotion) with ectoplasm forma- 

 tion. It follows therefore that the form of movement observed 

 in amebas depends invariably upon the streaming of the endo- 

 plasm accompanied by the formation of ectoplasm. 



There is however another element which, although it appears to 

 be a consequence of ectoplasm formation, must nevertheless be 

 included in any account of ameboid movement because of the 

 light it is bound to shed on the physical processes concerned in 

 streaming. This element is the thin outer layer which separates 

 the water in which the ameba lives from the ectoplasm. It is 

 the properties of this layer to which we may now 7 direct our 

 attention. 



That such a layer exists was indicated by observations of 

 Biitschli ('92) and Blochmann ('94), as already mentioned; but 

 neither of these authors stated definitely whether they considered 

 a third layer actually to exist or whether the ectoplasm as such 

 moved forward. Jennings ('04), as has been pointed out, con- 

 cluded that no third layer exists and that the particles clinging 

 to the outsides of amebas, which are carried toward the anterior 

 end, are carried by the ectoplasm. Gruber ('12) concluded how- 

 ever that an outer layer exists, composed of gelatinous substance, 

 which moves ahead at about the same rate as the ectoplasm 

 (P- 373)- According to Gruber's view the outer layer is a per- 

 manently differentiated layer of material. Schaeffer ('17), on 

 the contrary calls it a layer of protoplasm, which moves forward 

 faster than the forward advance of the ameba. 



