The Microscope and its revelations

J. Churchill, 1856 - 778 pagina's

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Pagina 775 - MR. JOHN HORSLEY. A CATECHISM OF CHEMICAL PHILOSOPHY; being a Familiar Exposition of the Principles of Chemistry and Physics. With Engravings on Wood. Designed for the Use of Schools and Private Teachers. Post 8vo. cloth, 6s. 6d.
Pagina 738 - The coal is macerated for about a week in a solution of carbonate of potash ; at the end of that time it is possible to cut tolerably thin slices with a razor. These slices are then placed in a watchglass with strong nitric acid, covered and gently heated ; they soon turn brownish, then yellow, when the process must be arrested by dropping the whole into a saucer of cold water, else the coal would be dissolved.
Pagina 198 - Diatomaceae, or tests of the like difficulty ; and although I should consider this as the highest object of ambition to our makers, if the performances of such lenses with test-objects were any fair measure of their general utility, yet as I think that I have demonstrated that the very conditions of their construction render them inferior in this respect for the purposes of ordinary microscopic research, I would much rather hold out the reward of high appreciation (we have no other to give) to him...
Pagina 261 - In the present state of Science, it would be very difficult, and is perhaps impossible, to lay down any definite line of demarcation between the two kingdoms ; since there is no single character by which the Animal or Vegetable nature of any organism can be tested. Probably the one which is most generally applicable, among those lowest organisms which most closely approximate to one another, is — not, as formerly supposed, the presence or absence of spontaneous motion, but the dependence of the...
Pagina 588 - These are arranged perpendicularly (or nearly so) to the surface of the laminae of the shell ; so that its thickness is formed by their length, and its two surfaces by their extremities.
Pagina 599 - Gasteropoda. plan of construction that seems common to by far the greater number of them ; and any considerable departures from this are uncommon. The small proportion of animal matter contained in most of these shells is a very marked feature in their character, and it serves to render other features indistinct...
Pagina 184 - ... knowledge of the class of bodies to which the particular specimen may belong. Not only are observations of any kind liable to certain fallacies arising out of the previous notions which the observer may entertain in regard to the constitution of the objects or the nature of the actions to which his attention is directed, but even the most practised observer is apt to take no note of such phenomena as his mind is not prepared to appreciate.
Pagina 197 - Now to the working microscopist, unless he be studying the particular class of objects which expressly require this condition, it is a source of great inconvenience and loss of time, to be obliged to be continually making these adjustments ; and a lens, which, when adjusted for a thickness of glass of 1-100", will perform without much sensible deterioration with a thickness either of 1-80" or of 1-120", is practically the best for all ordinary purposes.
Pagina 332 - Hooker, that the universal presence of this invisible vegetation throughout the South Polar Ocean is a most important feature, since there is a marked deficiency in this region of higher forms of vegetation; and were it not for them, there would neither be food for aquatic Animals, nor (if it were possible for these to maintain themselves by preying on one another) could the ocean-waters be purified of the carbonic acid which animal respiration and decomposition would be continually imparting to...
Pagina 381 - The universality of the appearance of these simple forms of fungi upon all spots favourable to their development, has given rise to the belief that they are spontaneously produced by decaying substances, but there is no occasion for this mode of accounting for it, since the extraordinary means adopted by nature for the production and diffusion of the germs of these plants adequately suffices to explain the facts of the case. " The number of sporules which any one fungus may develope is almost incalculable;...

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