Introduction to the study of biologyAppleton, 1872 - 163 Seiten |
Häufige Begriffe und Wortgruppen
Abiogenesis acid adult albuminous amongst animalcule animals animals and plants appear bioplasm buds carbon carbonic acid cavity cell-contents cell-wall cells characters chemical ciliated CLASS colony composed consists continuous gemmation dead definite deposits developed digestive distinct elements of reproduction exhibit existence external fact females fission Flowering Plants fluid Flustra Foraminifera formation fossils geological germs give rise groups higher animals homology homoplasy Hydractinia hydrogen Hydroid individuals inorganic kingdom known larva less living bodies living matter locomotive lower male minute morphological type mouth Natural Selection nervous system nitrogen occur organic compounds organic infusions organised ovule ovum oxygen parthenogenesis particles period physical basis pollen-tube polypite possess present primitive produced prothallus protoplasm Protozoa Pteropod regarded remain resemblance result segments sexual similar specialisation of functions species spontaneous structure SUB-KINGDOM substances surface term tion tissue true variations vegetable vital action viviparous whilst wholly young zoöids
Beliebte Passagen
Seite 53 - We come now to a still more extraordinary part of the imitation, for we find representations of leaves in every stage of decay, variously blotched and mildewed and pierced with holes, and in many cases irregularly covered with powdery black dots gathered into patches and spots, so closely resembling the various kinds of minute fungi that grow on dead leaves that it is impossible to avoid thinking at first sight that the butterflies themselves have been attacked by real fungi.
Seite 44 - ANALOGUE." — A part or organ in one animal which has the same function as another part or organ in a different animal. " HOMOLOGUE." — The same organ in different animals under every variety of form and function f.
Seite 57 - No term is more difficult to define than "species," and on no point are zoologists more divided than as to what should be understood by this word. Naturalists, in fact, are not yet agreed as to whether the term species expresses a real and permanent distinction, or whether it is to be regarded merely as a convenient, but not immutable, abstraction, the employment of which is necessitated by the requirements of classification. By Buff on, "species" is defined as "a constant succession of individuals...
Seite 19 - But it must be said that there are organisms which at one period of their life exhibit an aggregate of phenomena such as to justify us in speaking of them as animals, whilst at another they appear to be as distinctly vegetable.
Seite 63 - It is obvious, therefore, that a linear classification is not possible, since the higher members of each sub-kingdom are more highly organised than the lower forms of the next sub-kingdom in the series, at the same time that they are constructed upon a lower morphological type. In the words of Professor Allen Thomson, " it has become more and more apparent in the progress of morphological research, that the different groups form circles which touch one another at certain points of greatest resemblance,...
Seite 57 - species" is defined as "a constant succession of individuals similar to and capable of reproducing each other." DeCandolle defines species as an assemblage of all those individuals which resemble each other more than they do others, and...
Seite 135 - Until recently the great majority of naturalists believed that species were immutable productions. and had been separately created. This view has been ably maintained by many authors. Some few naturalists, on the other hand, have believed that species undergo modification, and that the existing forms of life are the descendants by true generation of pre-existing forms.
Seite 61 - Upon the whole, then, it seems in the meanwhile safest to adopt a definition of species which implies no theory, and does not include the belief that the term necessarily expresses a fixed and permanent quantity. Species, therefore, may be defined as an assemblage of individuals which resemble each- other in their essential characters, are able, directly or indirectly, to produce fertile individuals, and ivhich do not (as far as human observation goes) give rise to individuals u-hich vary from the...