An Introduction to Zoology |
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abdomen alimentary canal Ameba Anatomy animals antenna appendages basal become blastula blood body wall Cambarus cavity CELL DIVISION chemical chitinous chromosomes cilia cleavage cœlom colony conjugation consists containing contractile crayfish cuticle cytoplasm digestive divides dorsal drone earthworm ectoderm embryology Euglena excretory external female fertilized fibers functions gametes gastrula germ cells germ layers glands hive honey honeybee Hydra individuals insects intestine Journ known large number larvæ layer living longitudinal male mature membrane Metazoa micronucleus mitosis mouth muscles nematocysts nerve cord nervous system nucleus ovary pair Paramecia Paramecium parasite particles pass phylum physiological Planaria pollen pore posterior end present produced protoplasm Protozoa queen reaction Regeneration region segments side somite species sperm spermatocytes spermatozoa stages statocyst stimuli structure substance surface swim tentacles theory thorax tion tissue Triploblastic tube vacuole ventral vessel Volvox walking legs worker worm Zool Zoology zygote
Popular passages
Page 262 - Near villages and small towns I have found the nests of humble-bees more numerous than elsewhere, which I attribute to the number of cats that destroy the mice." Hence it is quite credible that the presence of a feline animal in large numbers in a district might determine, through the intervention first of mice and then of bees, the frequency of certain flowers in that district!
Page 285 - Given any species in any region, the nearest related species is not likely to be found in the same region nor in a remote region, but in a neighboring district separated from the first by a barrier of some sort, or at least by a belt of country, the breadth of which gives the effect of a barrier.
Page 262 - Hence we may infer as highly probable that, if the whole genus of humble-bees became extinct or very rare in England, the heartsease and red clover would become very rare, or wholly disappear. The number of humble-bees in any district depends in a great measure upon the number of field-mice, which destroy their combs and nests; and Col.
Page 303 - INSTINCT is usually defined as the faculty of acting in such a way as to produce certain ends, without foresight of the ends, and without previous education in the performance.
Page 306 - We know not where consciousness begins in the animal world. We know where it surely resides — in ourselves ; we know where it exists beyond a reasonable doubt — in those animals of structure resembling ours which rapidly adapt themselves to the lessons of experience. Beyond this point, for all we know, it may exist in simpler and simpler forms until we reach the very lowest of living beings.
Page 294 - ... that I attribute the modification of species exclusively to natural selection, I may be permitted to remark that in the first edition of this work, and subsequently, I placed in a most conspicuous position — namely, at the close of the Introduction the following words : "I am convinced that natural selection has been the main but not the exclusive means of modification.
Page 262 - I have also found that the visits of bees are necessary for the fertilization of some kinds of clover; for instance, twenty heads of Dutch clover (Trifolium repens) yielded 2,290 seeds, but twenty other heads, protected from bees, produced not one.
Page 36 - No other biological generalization, save only the theory of organic evolution, has brought so many apparently diverse phenomena under a common point of view or has accomplished more for the unification of knowledge.
Page 301 - The fittest are thus the most sociable animals, and sociability appears as the chief factor of evolution, both directly, by securing the well-being of the species while diminishing the waste of energy, and indirectly, by favouring the growth of intelligence.
Page 300 - With those animals which were benefited by living in close association, the individuals which took the greatest pleasure in society would best escape various dangers ; while those that cared least for their comrades, and lived solitary, would perish in greater numbers.