352 On Free-swimming Amoeh^. ['jSiUuS'iS^ 
tliis method may be employed with great advantage in determining 
the nature of minerals and chemical precipitates, when so small a 
quantity can be procured that other methods would almost or 
entirely fail to give satisfactory results. 
Y.—On Free-swimming Amoelm. By J. Gr. Tatem, Esq. 
Plate XVII. (upper portion). 
In the late autumn of last year, in some water which had been 
long kept, I noticed many small, transparent, gelatinous-looking 
atoms of about -^rVo -roVoj containing numerous relatively large 
greyish granules, progressing with a slow, oscillatory and revolving 
motion, preserving a more or less oval, though neither regular or 
permanent outline. Unable, with the magnifying power at 
command, to detect either the means of locomotion (though, from 
an uncertain flicker at the more rounded anterior extremity, a 
flagellum was believed to exist), or any notable structure, more 
perplexing creatures could scarcely have presented themselves. 
Accident, however, disclosed their true nature. An Oxytricha 
coming into violent collision with one of them, arrested its progress ; 
pseudopoda were instantly thrown out from the margin of contact, 
in a few moments withdrawn, its former shape resumed, and course 
pursued. Patiently following it in all its movements, I had the 
satisfaction, after a long interval, to see it ultimately settle down, 
flatten out, protrude on all sides short round pointed pseudopoda in 
a radiary manner, and assume in all respects a true replant 
Amoeba form. In Group A, I have endeavoured to give a correct 
representation of some of the forms in both its free swimming 
and creeping conditions. Many subsequent observations, as well 
as those obligingly made for me by my friend Mr. Clayton, con- 
firmed these facts, with the additional one, however, that alter- 
nations from the free to the reptant states were not infrequent. 
It should be noted that Amoebee of several recognized species 
abounded in this water, Amoeba ^rinee^s, A. Umax, A. dijffluens, 
A. guttula, and A. ^orrecta. 
More recently another and distinct species has been under 
observation ; larger, about -^-^ to globular or ovoid, of a 
ruddy brown colour, with a very fine long undulating flagellum, 
swimming with a slow, vacillating, semi-rotary motion, passing 
from time to time into the reptant stage, as a filmy Amoeba, with 
variable, mostly broad, laciniated pseudopoda— the flagellum re- 
