no TlMEHRI. 
these particles, for while, as a rule, the inorganic are 
passed over, the organic particles, which will serve as 
food, are retained. It is observed also that at whatever 
part of the body the particles touch, at that part they are 
received, any and every portion becoming a mouth for 
the time being, though the aperture closes up dire&ly 
after — in the same way that these particles, when they 
have yielded all their food matter, are thrown out from 
any part whatever of the little body to which they happen 
to be contiguous, the aperture again closing up as though 
it had never existed. Towards the central part of the 
Animalcule, the various particles are found aggregated, 
and they consist almost entirely of minute vegetable 
organisms. Among these, and towards the hinder part 
— hinder, that is, as regards the dire6lion of motion — of the 
Animalcule, will be noticed at intervals a rounded, glis- 
tening obje6l, which increases in size and then suddenly 
collapses, the fluid of which it was composed escaping 
and washing out, so to speak, the hinder portion of the 
organism. It thus appears and disappears at short and 
regular intervals. This is the body known as the 
contractile vesicle or vacuole, believed by some to be 
a rudimentary circulatory organ or heart, by others 
to be an excretory organ ; though, doubtless, it functions 
as both. Another small, rounded, clear obje6l, known 
as the nucleus ■, which is to be found in every Amoeba, 
may possibly be noticed ; it will readily be seen if a drop 
of magenta colouring solution be added to the liquid con- 
taining the specimen. The whole of the protoplasm 
becomes stained and the nucleus particularly so, becoming 
most visible. The fun6lions of the nucleus are not cer- 
