44 ACTION OF AUXETICS AND KINETICS 



found to be very persistent. The species described 

 as A. radiosa has been said to show neither nucleus 

 nor contractile vacuole, and although, in our case, 

 a single nucleus was occasionally visible, it was 

 more usual to find a number of spots which could 

 be stained, suggesting that the nucleus had broken 

 up into chromidia. The first type described above 

 appears to resemble the species described as Amoeba 

 poly podia. 



The act of mechanical transference of a loopful 

 of amoebae to a fresh medium often produces a 

 temporary condition similar to the second type, 

 which is maintained for about ten minutes, the 

 typical form of the amoeba being then gradually 

 resumed. This condition may also appear when 

 a culture of amcebae is exposed to a faradic current, 

 a few of the cells assuming this form as the 

 contact is made or broken, so that in about five 

 minutes nearly all the amcebae have become altered. 

 Young cultures are more liable to these changes 

 than old ones, and they may be produced on acid 

 or alkaline media. Doflein has described a similar 

 change in A. vespertilio, and Verworn describes 

 it as produced by caustic potash. On jellies con- 

 taining excessive amounts of salts, the amcebae 

 often project tentacles with bulbous ends, which 

 are waved about, and may become detached or 

 fragmented. 



It is possible that the mechanical interference 

 produces a certain amount of cell-death, which in 

 its turn sets free auxetics and kinetics, and thus 

 the appearance of these types of amoebae can be 

 explained. 



