ON INFUSORIA. 593 
might appertain to animals of the class of apod worms, since 
the body is elongated and symmetrical, without any visible 
articulations, and certainly without any appendages ; but it 
would be too much to assert this as certain, since observers 
say nothing of an intestinal canal, nor consequently of mouth 
or anus. Still the numerous movements of these organized 
bodies in determinate directions, will not permit us to doubt 
of their animality. It is the same with the vorticelle, of which 
we have spoken elsewhere, and which, though long ranked 
here, have a great analogy with the hydrz or polypi. There 
remain then the protei, and the volvoces, which we cannot refer 
to any known type. They, in fact, are organized bodies, 
without any determinate form, without any distinct organ, 
being nothing but a small mass of cellular tissue, in the meshes 
of which are contained fluids, and which is hardly condensed 
at the circumference to form an envelope, so that all the func- 
tions in these bodies, are reduced to immediate absorption of 
molecules, already prepared in the ambient fluid, and to ex- 
halation. ‘This may be considered as the term, the last link 
of animal life, where no organ is distinguishable. 
Be this, however, as it may, it clearly appears from what 
has now been said, that the class of the infusoria is totally in- 
admissible, because it contains animals of very different types. 
This, indeed, could not have been recognized previously to 
the establishment of the principle, that the general form of 
the body carries with it a determinate degree of organization, 
for in such little animals it is almost the form alone that can 
be perceived. Thus we may consider that the genera brachion, 
urceolaria, cercaria, furcularia, kerone, ‘trichocercus, and 
himantopus, really belong to the type of articulated animals, 
and particularly to the class of heteropods, order entomomos- 
traca. Many species of vibriones may be regarded as apod 
worms, and likewise the genera paramecia, and kolpoda; the 
rest of the vibriones, the cyclides, and, perhaps, the leucophes, 
VOL. XEN. aq 
