Sentence Examples


  • Reproduction and Ontogeny of the Hydromedusae.
  • The most striking general change has been against seeing in the facts of ontogeny any direct evidence as to phylogeny.
  • It is found in most of P all I of those Pteridophytes which we have other reasons for e considering as primitive types, and essentially the same Ontogeny type is found, as we have seen, in the independently with developed primitive conducting system of the mossPh.~logeny.
  • Polycycly was derived independently from monocycly in solenostelic and in dictyostelic forms. In the formation of the stem of any fern characterized in the adult condition by one of the more advanced types of vascular structure all stages of increase in complexity from the haplostele of the first-formed stem to the particular condition characteristic of the adult stem are gradually passed through by a series of changes exactly parallel with those which we are led to suppose, from the evidence obtained by a comparison of the adult forms, must have taken place in the evolution of the race, There is no more striking case in the plantkingdom of the parallel between ontogeny (development of the individual) and phylogeny (development of the race) so well known in many groups of animals.
  • From numerous investigations which have been made to trace the chromosomes through the various stages of the nuclear ontogeny of plant cells, it appears that the individuality and continuity of the chromosomes can only be conceived as possible if we assume the existence of something like chromosome centres in the resting nucleus around which the chromosomes become organized fon purposes of division.

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