H. W. KING ON AMCEB^:. 413 



together (Fig. 3, PI. XIX.), as frequently happens by the contrac- 

 tion of the animal, return to their normal rayed or divided ap- 

 pearance when the contraction is withdrawn. The endosarc is faint, 

 and only a little more marked in colour and consistency than the 

 ectosarc. 



I was unable to discern any nucleus or vacuoles, and the 

 protoplasms were free from granules and extraneous matter. 



In the specimens I observed there was no indication of any 

 diatoms or desmids or food usually found in Amoebae. 



By this it would seem the food is of a different nature to that 

 selected by Amoebae in general. And the endosarc occupying so 

 small a proportion of the whole being, and having so divided a 

 position within it, it does not seem possible that bodies such as 

 diatoms could be digested there, as only very minute organic food 

 appears capable of being enclosed in it. 



It is possible that this Amoeba may assimilate nutritive matter 

 in quite a different mode to that adopted by other and more highly 

 differentiated forms. Instead of absorbing solid and living matter 

 to be digested in the endosarc as in a stomach, they may absorb 

 nutriment in solution in the water in which they live. The 

 abeyant development of the endosarc may by this be accounted for. 



This Amoeba glides very quickly like a film over sedimentary 

 matter, to which it invariably travels, as by some attraction, and, 

 though apparently scarce, and not easily seen in consequence of 

 its flatness and transparency, it may be in reality very numerous 

 among the sedimentary matter in the water. And more, it is 

 possible that its real home is lower in the sediment, deeper in the 

 ever-increasing refuse falling from animal and vegetable life 

 domiciled near the tropical pool. And fluids charged with de- 

 composing ingredients would readily reach these organisms living 

 among the interstices of the flocculent matter that forms at once 

 their home and their source of food. Specimens of Amoeba radiosa 

 (Fig. 4, PI. XIX.) were also in the dipping from Colon, as well as 

 in the dippings from Port Limon and St. Lucia. 



It is interesting to note the wide distribution these animalcules 

 have, and more marked in extent than any of the other forms men- 

 tioned in this paper. This may be accounted for by this form 

 living principally upon and among the flocculent sediment to be 

 found in the water, where the long pseudopodia are well adapted 

 to pass among the interstices of the sediment, and there find support 



