Viscosity Changes of ProtoplasTn 167 



plasmalemma, which is much wrinkled. This usually occurs even 

 if the pressure on the cover glass is relieved as soon as the plasmasol 

 begins to flow out. Under these conditions, the continued flow 

 must be due to inward pressure produced by contraction in the 

 plasmagel or the plasmalemma. The fact that the plasmalemma is 

 much wrinkled after the plasmasol has flowed out, clearly indicates 

 that the pressure is due primarily to contraction in the plasmagel." 

 Edwards (1933, p. 11) found "If N/1 NaOH or KOH is applied at 

 any point on the surface of ameba there is an immediate rupture 

 of the ectoplasm at that point through which the endoplasm flows 

 until nearly all of it has passed into the surrounding medium. 

 Nothing remains except a few crystals which adhere to the inner 

 surface of the ectoplasmic sheath." 



The next important consideration concerns the local changes of 

 viscosity, gel layer into fluid or semifluid endoplasm, and endoplasm 

 into gel layer. This can be followed with ease in the ameba and 

 especially so in the slime mold under the oil immersion lens. These 

 changes are continually going on in all active cells and ameboid 

 organisms. In the ameba and the slime mold the numerous gran- 

 ules in the protoplasm act as indicators of such changes by the 

 presence or absence of Brownian movement or by their flow in 

 the streaming endoplasm. In both the ameba and the slime mold the 

 granules are enclosed in minute vacuoles in which they show a 

 limited Brownian movement even when the vacuoles are embedded 

 in gelated protoplasm. In the slime mold one can watch viscosity 

 changes in exceedingly minute areas with the oil immersion lens. 

 When the protoplasmic matrix gels, the vacuoles come to rest, and 

 when it solates, they show Brownian movement before they join the 

 endoplasmic streaming. There is no doubt about the changes in 

 viscosity, but the factors which bring them about are unknown. 

 Probably the factors which are responsible for the production of 

 the outer gel layer and inner less viscous endoplasm are internal. 



Local changes of external pressure may evidently produce local 

 changes of viscosity as indicated by the following quotation from 

 Mast (1931, p. 328), which applies to an ameba in a capillary tube. 

 "The following results were obtained: If the pressure against the 

 advancing end of an ameba in the tube is increased, the direction 

 of flow in the plasmasol immediately reverses, and the opposite end 

 begins to extend, usually in several different regions, a protuberance 

 with a hyaline cap forming in each region. These protuberances, 

 however, soon unite, resulting in the transformation of the posterior 



