Natural History of the Animalcules. 113 
structure of any kind whatever — being indeed one of the 
most primitive of the forms of life. To Animalcules of 
this kind, composed of utterly structureless protoplasm, 
the group name of Monera is applied, in allusion to 
their singleness of composition. < 
The next form, which may be termed the Vampire- 
animalcule (Vampyrella) , is also destitute of a nucleus 
and contra6lile vesicle, but its pseudopqdia or false-feet, 
instead of being thick and blunt, are fine and hair- 
like, or filamentous, protrusions of the protoplasm ; and 
when these filamentous pseudopodia are retra&ed, 
like the ordinary form they become mixed up with, 
or absorbed by, the ordinary protoplasm of the body, 
in which they are quite indistinguishable. These 
Vampire-animalcules are peculiar in the fa6l that they 
frequent the neighbourhood of certain minute plants, and 
feed upon them by attaching themselves to the cells of 
the plants by their pseudopodia, and then sucking out, 
or abstracting, the contents of the cells. 
We notice next a very striking type of organisation, one 
that we may distinguish as the Reticulate-animalcule. In 
this form, a nucleus and contractile vesicle are present as 
in the Proteus-animalcule, but the pseudopodia instead 
of being short, thick and blunt, are filamentous and very 
protrusible, and interlace repeatedly to form a netted 
strufture which has been compared to an " animated 
spider's web/' an apt comparison, since this network 
serves to ensnare food for the Animalcule. A minute 
shell, composed of lime, surrounds the body of the cell, 
and this shell is pierced with minute holes, so as to give 
passage to the pseudopodia. This calcareous shell may 
be like porcelain or like glass ; and, according to the 
P 
