22 ZOOLOGY 
appear, and that from forms resembling them all other organ- 
isms have originated. We can conceive at least of no simpler 
ancestral form; and if organized beings were originally pro- 
duced from the chemical elements which form protoplasm, 
one would be naturally led to suppose that the earliest form 
was like Protameba. It would follow from this fact that the 
Monera are as low as any plants, and that animals appeared 
contemporaneously with plants. 
Having studied a few typical forms of Monera, we are 
prepared to briefly define the group and tabulate the sub- 
divisions of the class. 
Cuass IL.—MONERA HaAnrcKe.. 
Beings consisting of transparent protoplasm, containing granules, some- 
times forming a net-work, but with no nucleus* or contractile vacuole ; 
capable of autumatically throwing out pseudopodia, and reproducing by 
simple self-division of the body-mass into two individuals, or by division. 
into a number of germ-like or spore-like young, which increase in size by 
absorption of the protoplasm of other organisms. 
Group 1. Gymnomonera, comprising the genera Protameeba, Protogenes, 
and Myxodictyum, which do not become encysted. 
Group 2. Lepomonera, which become encysted and protected by a 
case, as in the genera Protomonas, Protomyxa, Vampy- 
rella, and Myxastrum. 
Crass II.—Ruizoropa (Root Animaicules). 
General Characters of Rhizopods.—An idea of the form 
and internal structure of this group can be obtained by a 
study of Ameba, which may be found sliding over the sur- 
face of the leaves of plants growing in pools or ponds of 
fresh water. Our common Ameba has been studied by 
H. J. Clark. Fig. 10 represents this animal in the three 
more usual forms which it assumes. From time to time 
the sides of its body project either in the form of simple 
bulgings, or suddenly it throws out foot-like projections 
* Should a nucleus be found hereafter to occur in the Monera, the 
group should be merged into the Rhizopoda, and placed next to 
Ameba. 
