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THE AMCEBA : ITS STRUCTURE, DEVELOPMENT, 
AND HABITS. 
BY PROFESSOR W. C. WILLIAMSON, F.R.S. 
T HE peculiar direction which, modern microscopic in- 
quiries have taken has brought several hitherto obscure 
objects into prominent notice, because they happen to sustain a 
typical relation to an entire class. The Amoeba is one of these. 
The change which it effects in the outline of its gelatinous 
substance long since led to its acquiring the name of the 
Proteus animalcule ; but it was only when the study of Sponges 
and Foraminifera drew more general attention to the rhizopodous 
class that the true significance of the creature was recognized. 
It now runs no risk of being neglected, having already been 
the subject of many elaborate memoirs, as it doubtless will be 
of many more. The last few years have added much to our 
knowledge of this little creature, especially in consequence of 
the careful inquiries of Dr. Wallich and Mr. H. J. Carter. 
Nevertheless, we still require much more to be done before we 
can possess a correct view of the structure of the animal, since 
in some important points the two able observers referred to 
have arrived at different conclusions ; and when this is the case 
with naturalists who have given such persevering attention to 
the subject, both at home and abroad, those whose knowledge 
of it is less practical are scarcely in a position to arrive at 
decided opinions. Nevertheless, we may venture to analyse 
their labours, and endeavour to ascertain the present position 
of the question. 
There- are several points on which all naturalists are agreed ; 
whilst others must be regarded as moot questions. That the 
Amoeba is a microscopic jelly-like animalcule, common in fresh, 
and occasionally seen in sea water, is well known. Equally 
familiaris the tendency which the creature exhibits to incessant 
changes of shape, by pushing out some parts of its gelatinous 
substance and retracting others, so that of all known animals 
it best merits the designation of Proteus (figs. 1, 14, 15, 19). 
But behind these conspicuous phenomena are a multitude of 
