M. W. Jepps and C. Dobell 
353 
fragilis for our amoeba, but we can discuss the question of nomenclature 
most conveniently after we have described the organism itself. This, 
therefore, we shall now do. 
DESCRIPTION OF THE AjMOEBA. 
The amoeba is a very small organism, in the living state somewhat 
resemibling '‘Entamoeba'' nana in size and general appearance. Living 
individuals, when rounded, measure as a rule about Sq to 10/r in 
diameter, though larger forms (up to 12q,) also occur, and extremely 
minute individuals (down to 3-5p,) are not infrequent. Usually the 
dimensions are slightly less in fixed and stained organisms. 
The living amoeba moves actively by means of pseudopodia which 
usually differ in form from those of “EE nana, E. histolytica, and E. coli. 
The pseudopodia are extremely thin, hyaline, and leaf-like, and the 
ectoplasm of which they are composed is separated by a fairly sharp 
line of demarcation from the granular endoplasm of which the rest of 
the body mainly consists. (See Plate VII, figs. 1-3.) The broad flat 
pseudopodia are often irregularly lobed or marginally indented (Fig. 1). 
At times they suggest comparison with a bat’s wing; or when, as is 
not uncommon, they display three pointed lobes, their shape recalls 
that of an ivy-leaf. In progression the pseudopodia are confined to that 
side of the organism which is anterior; the rest of the body, containing 
the bulk of the protoplasm and its inclusions, remaining as a dense, 
rounded, posteriorly placed mass. Such individuals, when in active 
movement, somewhat resemble little snails (cf. Fig. 2). 
The endoplasm is finely granular and colourless in the living amoeba. 
It usually contains numerous food vacuoles enclosing small bacilli and 
cocci. The fixed and stained organisms show a distinct alveolar differen¬ 
tiation of their cytoplasm (cf. Figs. 4, 5, etc.): but healthy living indi¬ 
viduals, as a rule, possess no vacuoles save those containing food. 
There is no contractile vacuole. In iodine solution the amoebae sometimes 
show diffuse brown-stained patches, probably indicating the presence 
of glycogen; but whether this is contained in vacuoles or is in solution 
in the protoplasm we have not been able to determine. 
By far the most characteristic feature of the amoeba is its nuclear 
system. As a general rule the individuals are binucleate (cf. Figs. 4, 5, 
10, 11, 13). The nuclei are usually invisible in the living organism; but 
in stained specimens they are easily visible, and are seen to be exactly 
alike in size and structure (cf. Figs. 4, 5, etc.). In an individual of 
average size the nuclei are about 2q. in diameter: but as a general rule 
