I have already pointed out, in proof of the striking resemblance of the two cells, that the ova of many of the sponges were formerly regarded as parasitic Amoebae (Figure 1.
Large unicellular organisms like the Amoebaewere found creeping about inside the body of the sponge, and were thought to be parasites.
The oldest Amoebae lived isolated lives, and even the amoeboid cells that were formed by the segmentation of these unicellular organisms must have continued to live independently for a long time.
But gradually small communities of Amoebae arose by the side of these eremitical Protozoa, the sister-cells produced by cleavage remaining joined together.
But the further question now arises: "Whence came these first amoebae with which the history of life began at the commencement of the Laurentian epoch?
Studies on someAmoebae from the termite Mirotermes, with notes on some other protozoa from the Termitidae.
The amoebae are almost invariably found in the large intestine; one species, indeed, is termed Amoeba coli.
But to the trained biologist the amoebae are so transcendently higher than the other that he despairs of finding a bridge that can ever link up the two.
As these two young amoebae lie side by side under the microscope the thoughtful student will inquire--what has become of the parent organism?
Whereas at first there was one mature amoeba, now we have before us two young amoebae of the next succeeding generation.
Only a very few organic forms seem to be quite irregular, without any trace of symmetry, or constantly changing their formless shape, as we find, for instance, in the amoebae and the similar amoeboid cells of the plasmodia.
The same may be said of the internal flow of the plasm which we find in the plasmodia of the amoebae and mycetozoa, and in the endoplasm of many of the protophyta and protozoa.
Within the cytoplasm of the amoebae particles travel up and down in all directions.
As they are best observed in the common amoebae (naked nucleated cells of the simplest kind), they are called amoeboid movements.
Among the simplest fresh-water protozoa are the arcellina or thecolobosa (difflugia, arcella), little rhizopods that are distinguished from the naked amoebae by the possession of a firm envelope.
As vegetable cells even at an early stage enclose themselves within their hard, thick, and solid cellular shell, like that of the Amoebae in a state of rest (Fig.
The most ancient single-celled animals, being naked cells, could admit solid particles into the interior of their soft bodies, as do the Amoebae (Fig.
However, other Amoebae (like the one given in Fig.
These afterwards sank to the bottom, drew their fringes into their bodies, and gradually changed into the form of creeping Amoebae (like Fig 10 B).
The simple naked Amoebae are, next to the Monera, the most important of all organisms to the whole science of biology, and especially to general genealogy.
Many of these formless Amoebae have lately been recognized as the early stages of development of other Protista (especially the Myxomycetae), or as the freed cells of lower animals and plants.
There are also parasitic amoebae which live inside other animals.
When we place one of these amoebae in a drop of water under the microscope and examine it with a high power, it generally appears as a roundish particle of a very irregular and varying shape (Figures 1.
If you touch one of these creeping amoebae with a needle, or put a drop of acid in the water, the whole body at once contracts in consequence of this mechanical or physical stimulus.
It is for the following reasons that we regard the amoebae as the unicellular organisms which have special phylogenetic (or evolutionary) relations to the ovum.
In the sponges these mobile ova move about freely in the maternal body like independent amoebae (Figure 1.
Some kinds of theseamoebae can be seen with the naked eye, but most of them are microscopically small.
These creatures differ from the amoebae inasmuch as instead of pseudopods, they have developed tiny vibrating filaments, or thread-like appendages, which are used for drawing in their prey and for moving about.
Some of the amoebae (the diatoms, for instance) secrete solid matter from the water, and build therefrom shells or houses, which serve to protect them from their enemies.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "amoebae" in a variety of sentences. We hope that you will now be able to make sentences using this word.
