Viscosity Changes of Protoplasm 183 



spherical, but some, especially the larger ones, may be irregular 

 in shape. The smallest granules are rather highly refractive; they 

 appear to be similar to those which Mast (1925 and 1926) observed 

 in Amoeba and designated as 'alpha' granules, and they are similar 

 to the microsomes described by Chambers (1924) and which he 

 believes to be always present in protoplasm. Many of the granules 

 are contained in very small vesicles which bear close resemblance 

 to vacuoles." 



"The vesicles do not possess well-defined boundaries, and in 

 addition to containing one or more granules they seem to be filled 

 with a substance which is more completely hyaline and less viscous 

 than the surrounding hyaloplasm. That the material of these vesicles 

 is in a liquid state is indicated by the fact that these granules which 

 it surrounds are always in marked Brownian movement and can 

 very clearly be seen to move freely from place to place in the 

 vesicles." Granules not in vacuoles may at times exhibit very 

 slight Brownian movement. 



To this account, I might add a few observations. Minute areas 

 of solation frequently occur in the thin areas, and one can see the 

 little vacuoles with their contained granules move out into the flow 

 of newly formed endoplasm. When endoplasm gels again in such 

 areas, the vacuoles can be noted as they come to rest. This indicates 

 that they either have or acquire a definite wall when the hyaloplasm 

 surrounding them solates. It thus seems quite probable that even 

 in the streaming endoplasm of the large channels the vacuoles persist. 

 One can sometimes detect them when the endoplasm comes to rest. 

 Some of the granules noted by Camp were not in vacuoles. These 

 I have also noted in great numbers. They are considerably smaller 

 than the vacuoles, are grayish in color, and are best seen in areas 

 that are too thin to accommodate the vacuoles. They stain with 

 Janus green and are mitochondria. They occur all through the gel 

 layer and endoplasm. The contractile vacuoles also noted by Camp 

 and others are often quite numerous in the neighborhood of the 

 thin areas and throughout the gel layer. They, like the granule-con- 

 taining vacuoles, are freed and carried into the endoplasmic stream 

 when the surrounding hyaloplasm solates. They also either have 

 or acquire a definite wall. 



Camp does not mention the nuclei which are present in great 

 numbers. They are small, round, and have a single, rather large, 

 gray nucleolus. They are very difficult to see, because the nucleo- 

 plasm is optically similar to the gelated hyaloplasm, but once one 



