THE EFFECT OF MEDIA OF DIFFERENT DENSITIES 

 ON THE SHAPE OF AMOEBAE 



MARY J. HOGUE 



From the Department of Zoology, Wellesley College 



NINE FIGURES 



For a long time the different species of amoebae were deter- 

 mined by their general shape and by the form of their pseudo- 

 podia. Then Scheel showed in 1899 that Amoeba radiosa is not 

 a distinct species but merely an early stage in the life history of 

 Amoeba proteus. The long slender pseudopodia of A. radiosa 

 give place to the lobose ones which are typical of amoeba proteus 

 and become its organs of locomotion. 



While working with an amoeba of the limax group I noticed 

 a great variety in the form of the animals, the shape of their 

 pseudopodia, and also in the size of the individuals. It was 

 with a \dew of determining what the factors are which bring about 

 these differences that the present work was begun. 



In an interesting paper on the growth of the epithelial cells 

 of the frog's skin, Uhlenhuth ('15) has shown that when the cells 

 are grown on media of different consistencies there is a distinct 

 difference in their shape. In a firm medium the epithelial cells 

 are polyhedral and remain united in a compact membrane. In 

 the semi-firm medium the cells which stray out are fusiform 

 in shape, while in the soft medium the cells are fusiform or thread- 

 like in shape. With these experiments in mind I determined 

 to trv^ raising amoebae on media of different densities to see 

 whether they too would be affected in the same way as the epi- 

 thelial cells of the frog skin. 



565 



