The American Naturalist, Volum 39,Part 2Essex Institute, 1905 |
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Frases i termes més freqüents
Acanthias adductor animals Annals of Bot apogamy bivalent chromosomes body Bull central stylet centrosomes centrospheres chamber character chiefly chromatin chromatophores chromo chromosomes Coccidia color cytoplasm distribution division dorsal eggs embryo-sac evidence fertilization fibers fish fission forms fusion gall gamete gametogenesis gametophyte genera genus gill groups growth ring hagfish heterotypic mitosis hybrid inserted intestinal kinoplasm larvæ longitudinal lower walls material Medullary rays membrane mitosis morphology muscle narrow nuclear nuclear fusions nucleolus nucleus number of chromosomes oblong ocelli organs origin oval pairs paper parasites parthenogenesis penis-sac plants Populus posterior present Proc protoplasm protoxylem radial reduction phenomena region Salicaceæ Salix sexual showing side species specimens sperm spindle spirem spore spore mother-cell sporogenesis sporophyte sporophytic chromosomes Strasburger structure studies stylets surface synapsis tangential terminal walls thallophytes tion tracheids transverse Ueber ventral constrictors vessels wood cells wood parenchyma
Passatges populars
Pàgina 859 - ... in no wise connected with galls. "Nothing gives us a- better idea of the prodigious exuberance of insect life, and of the manner in which one insect is often dependent upon another for its very existence, than to count up the species which haunt, either habitually or occasionally, one of these willow-galls, and live either upon the substance of the gall itself or upon the bodies of others insects that live upon the substance of the gall.
Pàgina 777 - Bulletin from the Laboratories of Natural History of the State University of Iowa, vol.
Pàgina 773 - No. 1391. On a collection of fishes made in Korea, by Pierre Louis Jouy, with descriptions of new species. By David Starr Jordan and Edwin Chapin Starks.
Pàgina 886 - ... climatic centers which correspond in general with the centers of plant distribution. Further, the distribution of grassland, prairie, open forest, and dense forest regions is clearly indicated. This is explained by the fact that such ratios involve four climatic factors which are of the greatest importance to plant life, viz., temperature, relative humidity, wind velocity, and rainfall.
Pàgina 617 - Hsmosporidia, however, the male and female cells must be removed from the blood of the host to insure further development. This removal is effected by a blood-sucking arthropod, which takes the parasites into its alimentary canal. Here they mature, the male cells forming each a number of microgametes, the female cells each a single macrogamete or egg. The microgametes fertilize the macrogametes, which then metamorphose into elongated elements, the ookinetes. The ookinete pierces the intestinal epithelium...
Pàgina 617 - The trophozoite. growing at the expense of the blood cell, soon breaks up into a number of merozoites. By the disintegration of the blood cell, the merozoites fall into the blood stream. Forthwith they attack new blood cells and the process (schizogony) is repeated. The Increase is therefore by geometrical ratio, and, as Mlnchln says : " It is evident that reproduction at this rate could only continue indefinitely in the ichor of an infinite host.
Pàgina 774 - P. 1402. Descriptions of new genera and species of mammals from the Philippine Islands. By Edgar A. Mearns.
Pàgina 772 - La faune et la flore glaciaires du plateau de la Baraque Michel [Bull.
Pàgina 777 - The fish parasites of the genus Argulus found in the Woods Hole region.
Pàgina 837 - FH (98) A catalogue of the Cretaceous and Tertiary plants of North America.