Thus, to begin with, the animal pedigree is divided into two very distinct grades, the Protozoa and the Metazoa.
Anatomic, Berlin, 1845) as that of a primary division of animals, the others recognized in that treatise being Protozoa, Zoophyta, Vermes, Mollusca and Vertebrata.
Linnaeus applied the Latin term Vermes to the modern zoological divisions Mollusca, Coelentera, Protozoa, Tunicata, Echinoderma (qq.v.), as well as to those forms which more modern zoologists have recognized as worms. As a matter of convenience the term Vermes or Vermidea is still employed, for instance in the International Catalogue of Zoological Literature and the Zoological Record, to cover a number of wormlike animals.
GASTROTRICHA, a small group of fairly uniform animals which live among Rotifers and Protozoa at the bottom of ponds and marshes, hiding amongst the recesses of the algae and sphagnum and other fresh-water plants and eating organic debris and Infusoria.
The chromatin is distributed throughout the cytoplasm in the form of granules which may be regarded as a distributed nucleus corresponding to what Hertwig has designated, in protozoa, chromidia.
Animals suffer from the ravages of bot flies (Oestridae) and gad flies (Tabanidae); while the tsetse disease is due to the tsetse fly (Glossina morsitans), carrying the protozoa that cause the disease from one horse to another.
The plankton is divided into (a) the Zoo-plankton (such as the minute crustacea and the eggs and larva of fishes and many other marine animals); and (b) the Phyto-plankton, that is, the minute algae, diatoms, peridinians, some flagellate protozoa, spores of alga, etc. The investigation of the plankton from a new point of view, begun by Hansen in 1889, was continued by Lohmann at Kiel, by Cleve in Sweden, by Gran and Ostenfeldt in Norway and Denmark, and by Herdman, Allen and others in England.
Lime is, in fact, absorbed to an enormous extent by fishes, molluscs, crustacea, calcareous algae and sponges, starfishes, sea-urchins and feather stars, many polyzoa and a multitude of protozoa (mainly the foraminifera).
' Classes: Rotifera, Polygastria (the Protozoa of recent authors).
We have analogies to this in the two nuclei of some of the protozoa, the one being solely for the purpose of propagation, the other being associated with the functional activities of the cell.
Many cancer-parasites have been described in cancerous growths, including bacteria, yeasts and protozoa, but the innumerable attempts made to demonstrate the causal infective organism have all completely failed.
"Protozoa" in Ency.
The structural features which the Mollusca do possess in common with other animals belonging to other great phyla of the animal kingdom are those characteristic of the Coelomata, one of the two great grades (the other and lower being that of the Coelentera) into which the higher animals; or Metazoa as distinguished from the Protozoa, are divided.
Unlike the cells of Protozoa, these embryonic cells of the Metazoa do not remain each like its neighbour and capable of independent life, but proceed to arrange themselves into two layers, taking the form of a sac. The cavity of the two-cell-layered sac or diblastula thus formed is the primitive gut or arch-enteron.
In comparing algae with the great archegoniate series which has doubtless sprung from them, it is natural to inquire to what extent, if any, they present evidence of the existence Peridiniaceae Diatomaceae Cryptomonadaceae - Hydruraceae - EuPHAEOPHYnEAE Protozoa Flagellata protomastigina...
Simple protozoa appear in the form of Radiolaria; Lithistid sponges are represented by such forms as Archaeoscyphia, Hexactinellid sponges by Protospongia; Graptolites (Dictyograptus (Dictyonema)) come on in the higher parts of the system.
From the more complex colonial Protozoa the Coelentera are readily separated by their possession of two distinct sets of cells, with diverse functions, arranged in two definite layers, - a condition found in no Protozoan.
The old criterion by which they and other Metazoa were once distinguished from Protozoa, namely, the differentiation of large and small sexual cells from each other and from the remaining cells of the body, has been broken down by the discovery of numerous cases of such differentiation among Protozoa.
- Scaphopoda feed on the lowest marine organisms such After Kowalewsky, in Lanas Diatoms, Protozoa, &c. There are 150 's Treatise on Zoology, living and about 275 known fossil species.
They belong to the group of Protozoa, and, as already explained, have a double cycle of existence: (I) a sexual cycle in the body of the mosquito, (2) an asexual cycle in the blood of human beings.
SPOROZOA, a large and most important section of the Protozoa, all the members of which are exclusively parasitic in habitat.
A great variety of forms were described by other observers, but they were not separated as a class from the unicellular organisms (Protozoa) with which they usually occur, until the appearance of C. G.
The Rotifera are all aquatic, the majority dwelling in fresh water with Protozoa and Protophyta, as well as Entomostracous Crustacea.
Wright, "Protozoa in a case of tropical ulcer (Delhi sore), " Journ.
The existence of ciliated micrococci together with the formation of endospores - structures not known in the Cyanophyceae - reminds us of the flagellate Protozoa, e.g.
The geographical distribution is cosmopolitan, as is the case with Protozoa and Protophyta of similar habits.
Protozoa' (various groups included).
Orders: Rotifera, Homogenea (this includes the Protozoa of recent writers and some Protophyta).