274 PBOF. ALLMAIf ON THE EECENT RESEARCHES 



posed to be exclusively aquatic, have terrestrial representatives*. 

 The Amoeba terricola of Greeff occurs in earth and dry sand. It 

 has an irregularly spherical form, with blunt nodular projections 

 and a dull glassy appearance. It looks like an irregularly shaped 

 fragment of silica, and might be easily passed by as a grain of sand. 



A more careful examination shows within it yellow granules, 

 which are in lively motion, streaming here and there through the 

 soft protoplasm. 



Its body is composed of two substances, an outer hyaline layer 

 of firmer, consistence, and an inner granular, softer, and more fluid 

 parenchyma. Nowhere among the aquatic Amoehce is the differ- 

 ence between these two constituents so strongly defined as here. 

 The hyaline outer layer is the chief source of the contractility. 



The motions of the animal are peculiar and diiFerent from those 

 of the aquatic Amoehce. It does not, like these, appear to flow over 

 the surface on which it lies, but raises itself on the projections 

 from its body, which, unlike the pseudopodia of the aquatic 

 Amoelce, are firm and strong enough to support it. While thus 

 balanced, the influx of the granular parenchyma towards certain 

 parts of the periphery disturbs the equilibrium and causes the 

 whole to roll over. Its motion is thus a rolling instead of a creep- 

 ing one. In some cases the peculiar villous condition first noticed 

 by Wallich and Carter in certain aquatic Amoehce was present on 

 the posterior end of the body. 



No special membrane is to be found on the outer layer ; and 

 Greeff", in opposition to Auerbach, denies the presence of such a 

 membrane, not merely on his terrestrial Amoeha, but on the aquatic 

 ones. 



A number of clear vacuoles of different sizes may be seen float- 

 ing in the soft parenchyma. These are very variable in size and 

 number. They are carried about by the currents, and may be 

 seen in one and the same individual to change from minute to 

 minute. When two vacuoles come in contact they frequently 

 run together into a single one, which may still further combine 

 with others. Occasionally one of the large vacuoles may be seen 

 to approach the periphery of the parenchyma and then suddenly 

 disappear as if it had been emptied outwards. After a few seconds, 

 however, we find in its place a great number of very small vacuoles, 

 which again gradually unite with one another until, instead of a 

 * "Ueber einige in der Erde lebenden Amoeben" &c., Arch. f. mikr. Auat. 

 vol. ii. 1866. 



