MONERA. a1 
and assimilative ; (4) it is metabolic and secretory in the 
sense that the Moner digesis and separates the portions 
necessary for food from those which it rejects as waste ; (5) 
it is respiratory, the changes involved in taking food, es- 
pecially oxygen, causing the production of and excretion of 
carbonic acid ; (6) it is reproductive. 
It is difficult to conceive of a simpler form of life than 
Protameba or Protomonas. Are the Moners animals or 
plants, or do they represent a neutral division or group of 
forms? It was formerly thought that Amceda was the sim- 
plest possible form of life, but we shall see that that animal 
isan undoubted organism, possessing a permanent organ, 
the nucleus. Moreover, the Amoeba intergrades with the 
other Rhizopods which are undoubted animals, while the 
simplest Monera have no characters which absolutely sepa- 
rate them on the one hand from the plants or on the other 
from the animals. ‘Their relation to the plants is seen in 
the fact that, besides the resemblance to the lowest plants, 
the cyst of Protomonas is composed of cellulose, while the 
granular contents of the body become colored with chlo- 
vophyll.* 
For these reasons, Haeckel, the discoverer of the Monera, 
regards them as neutral beings, neither plants nor animals. 
But by comparison with other Protozoa, we shall see that 
the Monera only differ from the monads and Amebe by the 
absence of a nucleus. This may yet be found to occur in 
the Monera, and from this fact we separate the group only 
provisionally from the Rhizopoda. The Gregarine also pass 
through a true Moner-stage. This indicates that the 
Monera are allied rather to animals than plants. Another 
point of difference from plants is the fact that, like the 
Ameba, they engulf living plants (desmids, etc.) and ani- 
mals (Infusoria), the only plants known to do this being the 
singular Myxomycetes, whose position is uncertain, some 
naturalists (Allman) regarding it as an animal. 
It is probable that the Monera were the earliest beings to 
* On the other hand, cellulose occurs in the integument of Tunicates, 
and various parts of Articulates and Vertebrates, while chlorophyll 
occurs in the Infusoria and Hydra. 
