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abdomen Acalephae adapted alimentary canal animal animalcule Annelid aperture apparatus appearance appendages arrangement arterial attached become blood body branches branchial calcareous capsule cavity cells centre cilia circulation colour communication composed consists contained creature Crustacea delicate derived digestive digestive apparatus dilated disk distinct dorsal eggs embryo enclosed exhibit existence external extremity female fibres filaments fishes fluid furnished ganglia ganglion genera horny Infusoria insects integument interior internal intestine larva lateral layer limbs locomotive longitudinal male margin mass membrane ment microscope minute mouth movements muscles muscular Myriapoda nerves nervous observed oesophagus organs orifice ovary oviduct ovum pair pedicle polyp polypary portion posterior proboscis pupa remarkable reproductive resembling respiration respiratory secretion seen segments shell side situated skeleton species spermatozoa spines stomach structure substance suckers surface tentacles tentacula termination thorax tion transparent transverse trunks tube vascular ventral vertebrae vesicle vessels viscera viscus worm
Seite 548 - Introduction to Conchology ; or Elements of the Natural History of Molluscous Animals. By GEORGE JOHNSTON, MD, LL.D., Fellow of the Royal College of Surgeons of Edinburgh, author of ' A History of the British Zoophytes.
Seite 656 - The eye itself differs in many points of structure from that of terrestrial Vertebrata, its organization being of course adapted to bring the rays of light to a focus upon the retina in the denser element in which the fish resides ; the power of the crystalline lens is therefore increased to the utmost extent, and the antero-posterior diameter of the eye-ball necessarily contracted in the same ratio, in order that the retina may be placed exactly in the extremely short focus of the powerful lens.
Seite 181 - ... structure of the penis. The result of our own examination, in more than one species, is different still. We have always found the earthy matter forming a jointed calcareous tube. This tube, which is about the thickness of a surgeon's probe, is composed of rings of calcareous substance connected by membrane, so that viewed externally it is not unlike the windpipe of a small animal.
Seite 800 - ... with each other. The medulla spinalis is surrounded with a network of arteries in the same manner, more especially where it comes out from the brain, where a thick substance is formed by their ramifications and convolutions ; and these vessels most probably anastomose with those of the thorax.
Seite 244 - These Annelids are annuals : the term of existence is completed when the organic cycle is once accomplished. They are born during the latter months of one summer, and survive the winter, attain to the maturity of growth, reproduce the species, and die by the spontaneous subdivision of the body into fragments on the arrival of the same season of the succeeding year.
Seite 341 - ... the sexual intercourse of one original pair serves for all the generations which proceed from the female for a whole succeeding year.
Seite 46 - Thus the Paramecium aurelia, if well supplied with food, has been observed to divide every twenty-four hours, so that in a fortnight, allowing the product of each division to multiply at the same rate, 1 6,384 animalcules would be produced from the same stock...
Seite 475 - ... and with the greatest rapidity- Sometimes they simply rotate upon their axis, or they tumble over and over ; or selecting a fixed point they whirl round it in rapid circles, carrying every loose particle after them- Others creep...
Seite 35 - As long as the animalcule continues free from annoyance, the trichocysts undergo no change, but when subjected to external irritation, as occurs during the drying away of the surrounding water, or the application of acetic acid or other chemical irritant, or the too forcible action of the compressor, they become suddenly transformed into long filaments, which are projected from all parts of the surface of the animalcule (fig. 13); and it is these filaments which, being mistaken for cilia by Colin...
Seite 189 - ... in which they were confined), cut off with scissors successive portions of the dorsal covering of the body, so as to expose the visceral cavity ; but, so far from the rest of the animal appearing to be conscious of the mutilation, not the slightest evidence of suffering was visible: the suckers placed immediately beneath the injured part were invariably retracted ; but all the rest, even in the same ray, still continued their action, as though perfectly devoid of participation in any suffering...