44 



PROTOZOOLOGY 



podia, as there are transitional pseudopodia between any two of 

 them. For example, the pseudopodia formed by Arcella, Lesquer- 

 eusia, Hyalosphaenia, etc., resemble more lobopodia than filopodia, 

 though composed of the ectoplasm only. The pseudopodia of Actino- 

 monas, Elaeorhanis, Clathrulina, etc., may be looked upon as 

 transitional between rhizopodia and axopodia. 



Fig. 6. Portion of Adinosphaerium eichhorni, X800 (Kiihn), ar, axial rod; 

 cv, contractile vacuole; ec, ectoplasm; en, endoplasm; n, nucleus. 



While the pseudopodia formed by an individual are usually of 

 characteristic form and appearance, they may show an entirely 

 different appearance under different circumstances. According to 

 the often-quoted experiment of Verworn, a limax amoeba changed 

 into a radiosa amoeba upon addition of potassium hydrate to the 

 water (Fig. 7). Mast has recently shown that when Amoeba proteus 

 or A. duhia was transferred from a salt medium into pure water, the 

 amoeba produced radiating pseudopodia, and when transferred 

 back to a salt medium, it changed into monopodial form, which 

 change, he was inclined to attribute to the difference in the water 

 contents of the amoeba. In some cases during and after certain in- 

 ternal changes, an amoeba may show conspicuous differences in 

 pseudopodia (Neresheimer). As was stated before, pseudopodia occur 

 widely in forms which are placed under classes other than Sarcodina 

 during a part of their life-cycle. Care, therefore, should be exer- 



