THE SARCODINA 



8 9 



In addition to the contractile vacuoles the Sarcodina occasionally 

 possess gas vacuoles, which were first made out in Arcella, but which 



GUI 



Fig. 49. Am<eba proteus and the contractile vacuole. 



A. The vacuole (v) is in the form of minute vesicles in the region of contraction. B. Three 

 minutes later. C. Two minutes later still (two vesicles have united). D, Two vesicles previous 

 to union near the nucleus (). E. The single vacuole becoming separated from the nucleus. F. 

 The vacuole at the posterior end previous to contraction. G, H, I, and y. Four stages in the con- 

 traction of the vacuole. 



have since been shown to be quite general in the group (Claparede 

 and Lachmann, Engelmann, Butschli, Entz, Rhumbler). The gas 



