33 



Figure 9. Amoeba bihi. a, the ameba in locomotion, showing the 

 ectoplasmic ridges, nucleus, contractile vacuole. b, the transition stage 

 between the rayed stage (which resembles that of radiosa, Figure 5, p. 30, 

 somewhat) and the stage shown at a. The whole of the ameba flows into 

 the broad pseudopod with the arrow. Length of a, 90 microns. 



In size it is about midway between the latter species and striata. 

 It always has a number of prominent longitudinal ridges on its 

 upper surface. Its mode of streaming is essentially like that of 

 striata or sphaeronucleosus. When this ameba is disturbed and 

 left suspended in the water, it throws out four or five or more 

 long slender pseudopods composed entirely of hyaloplasm, ex- 

 cepting a bulbous base which consists of granular endoplasm. 

 The pseudopods are cylindrical with tapering ends. They are 

 very rigid, and once formed, persist for a considerable length of 

 time. When these pseudopods are about to be retracted, the wall 

 weakens at some point and then crinkles while the distal part 

 of the pseudopod bends, often at a decided angle. The crinkling 

 of the wall continues up and down the pseudopod while it is 

 slowly being withdrawn. These pseudopods, as well as those of 

 the rayed state in radiosa and bigemma, are not pseudopods of 



