16 
Quarterly Journal. 
the appearance of the pseudopodia, or arms, which they 
protrude, are not very far advanced in the scale of animal 
life. Further on are the Infusoria proper, which have cilia, 
or hairs, by means of which they move and procure their 
food. They have a definite shape, and in the bodies of some 
of them are vacuoles and a vesicle which is contractile, and 
in some expands and contracts in rhythmical intervals, but 
its use in their economy is not perfectly known. The 
Vortieella are small, bell-sliaped infusoria, which are anchored 
by a long stalk that has the power of coiling up suddenly 
when alarmed, and slowly extending again : their forms are, 
however, so varied that 1 cannot here attempt a description 
of them, but will proceed to notice those I have seen. 
Infusoria may be found in almost any drop of water, yet 
they are really veiy difficult subjects to treat of properly, 
unless one has plenty of time to devote to their special 
study; they cannot be preserved, and it takes a considerable 
time to make sure of their forms and structure, especially as 
to the disposition of their cilia. They are always moving 
about so quickly that only occasionally can their details be 
properly seen, and then perhaps only for an instant; they 
are, therefore, very difficult subjects to draw, and •without 
accurate drawings it is impossible to be certain of their 
identity; memory is not sufficiently trustworthy, and as to 
details, the best descriptions cannot compare with correct 
drawings. 
The history or biology of their forms (especially of the 
most minute) has lately been made known in some very 
valuable papers by Messrs. Dallinger and Drysdale, in the 
Monthly Microscopical Journal. These papers seem to 
point to the inevitable conclusion (although they treat only 
of the minutest forms yet known) that many, probably 
most , of the forms drawn and described as distinct species, 
may only be the different forms of comparatively few species 
in the various stages of their lives. I can only speak of 
those that I have seen as different foi'ins, attempting very 
little in the way of naming them. It does not fall to the 
lot of many in Australia to be enabled to keep the same 
forms under long-continued observation, as described in the 
papers above alluded to ; and until we can do the same our 
knowledge of the majority of the species in this class must 
remain in its present unsatisfactory state, while careful 
observation would clear up many points. 
