A first book in organic evolutionShute, D. Kerfoot (Daniel Kerfoot)
Science
A first book in organic evolution
Shute, D. Kerfoot (Daniel Kerfoot)
Evolution
The goal of evolution seems to be men with Great Minds of High Character.
_There is nothing great in the world but man, nothing great in man but
mind, and nothing great in mind but character._
SECTION VII.
CLASSIFICATION OF ANIMALS AND PLANTS.
A SYNOPSIS OF THE ANIMAL KINGDOM.
In order that the reader may appreciate to some extent the relative
positions of the different groups of animals, extinct and living, in the
scale of life, the following brief classification may be useful. This
synopsis is especially intended to help readers who are not familiar
with elementary zoölogy to understand the significance of the different
types of animals found in the strata of different geologic periods, and
more particularly to grasp the meaning of the Diagram of Development. The
animals are usually mentioned in the order of their position in the scale
of life, commencing with the lowest and simplest.
SYNOPSIS OF GROUPS.
A. PROTOZOA. Unicellular animals, dissociated, or associated in simple,
loose colonies of similar organisms. Many have an exoskeleton of lime,
flint, or other material. Reproduction by fission and by temporary or
permanent conjugation.
B. METAZOA. Multicellular animals, consisting of a large number of cells
associated together to form single, complex individuals. The cells of
an individual are usually differentiated into several kinds performing
special functions. Reproduction in the higher forms is sexual; in the
lower forms it is often by budding as well as sexual.
SYNOPSIS OF THE BRANCHES OF ANIMALS.
GROUP A. PROTOZOA.
Branch I.—=Protozoa.= Characteristics already defined.
Class 1.—_Monera._
Class 2.—_Rhizopoda_: Amœba, Arcella, Foraminifera, Difflugia, Quadrula.
Class 3.—_Gregarinida_: Gregarina.
Class 4.—_Infusoria_: Noctiluca, Paramecium, Stylonychia.
GROUP B. METAZOA.
Branch II.—=Porifera.= Sponges are animals with their cells arranged in
two well-defined layers, one of which is internal (endoderm) and the
other external (ectoderm). There is a middle stratum of cells (mesoglœa)
which does not attain to the definiteness of a mesoderm. Sponges do not
possess a body cavity (cœlome); they possess, essentially, a bilateral
symmetry. The body varies greatly in shape, and is traversed by canals
having large openings (oscula) and numerous small openings (pores) on
the surface. The ectoderm is continued through the pores into afferent
canals; the endoderm cells line most of the internal (efferent) cavities,
and are mostly flagellate; the mesoglœa contains a skeleton of flint,
lime, or spongin. Reproduction may be by budding or sexual (either
hermaphroditic or unisexual).
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