The Monthly Microscopical Journal: Transactions of the Royal Microscopical Society, and Record of Histological Research at Home and Abroad, Volume 8

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Robert Hardwicke, 1872 - Microscopy
 

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Page 127 - the ultimate parts of the organism are not cells nor nuclei, but the minute molecules from which these are formed. They possess independent physical and vital properties, which enable them to unite and arrange themselves so as to produce higher forms. Among these are nuclei, cells, fibres, and membranes, all of which may be produced directly from molecules. The development and growth of organic tissues is owing to the successive formation of histogenetic and histolytic molecules. The breaking '...
Page 31 - The eggs are readily fecundated by the artificial method. After they have been in the water a few minutes they adhere to any object which they touch. The development of the embryo can be observed in progress at the end of one hour. On the seventh day they hatch. At first the young fish are 0m.
Page 21 - J-in., and }-in., to the oculars nearest the powers of 5, 7J, 10, 12J, 15, 20, 25, 30, and 40 ; and the writer is satisfied, by experience of its convenience, that this nomenclature needs only a trial to secure its adoption by all those who use the microscope for other purposes than amusement. Of course, any microscopist, having determined the power of an objective, and the powers of the microscope when that objective is used with his various oculars, can obtain the powers of his oculars by dividing...
Page 199 - Logan in 1859, is it not rash to attempt to explain it away now, when certain minute internal structures, corresponding to what might have been expected on the hypothesis of its organic origin, are added to it ? If I affirm that a certain mass is the trunk of a fossil tree, and another asserts that it is a concretion, but professes to be unable to account for its form and its rings of growth, surely his case becomes very weak after I have made a slice of it, and have shown that it retains the structure...
Page 127 - In nature, the breaking down of one substance is the necessary step to the formation of another, and the histolytic or disintegrative molecules of one period become the histogenetic or formative molecules of another. This fact constitutes the basis of the law which I shall subsequently seek to establish. II. The author pointed out, in the second place, that these molecules are governed by forces, which induce among them a variety of movements, and cause them to combine in definite ways. This force,...
Page 201 - I do not deny that the tubulation is often imperfectly pre-served, and that in such cases the casts of the tubuli may appear to be glued together by concretions of mineral matter, or to be broken or imperfect. But this occurs in all fossils, and is familiar to any microscopist examining them. How difficult is it in many cases to detect the minute structure of Nummulites and other fossil Foraminifera ? How often does a specimen of fossil wood present in one part distorted and confused fibres or mere...
Page 34 - ... with numerous fine threads radiating from the nucleus, or the germinal dot As the frustule increases in width, one portion slips out from the other, and sometimes successive additions of siliceous matter are made to the edges of the box, somewhat analogous to the successive additions to the edge of the shell of a mollusc. When the widening of the frustule has reached a certain extent, the lining membrane, nt the places which would be exposed if the two portions were wholly to slip apart, infolds.
Page 91 - Nostoc minimum (Currey),! but in it the cells are described as quadrate with a sinus at each side, lending a crenate outline to the filaments, and the heterocysts are large, whilst here the cells are orbicular or for a time slightly flattened at the junctions, and the heterocysts are but slightly wider, though longer than the ordinary cells. This plant is probably identical with Nostoc paludosum (Kiitz.), though as regards anything to be deduced from the heterocysts Kiitzing is silent. But the interesting...
Page 17 - A positive ocularf or the eye-lens of a negative one is used as a simple microscope with which to read off the measurement. If a separate piece of apparatus were to be made for the purpose of measuring these powers, a positive ocular with micrometer attached would doubtless be preferred, it being placed by means of the drawtube or some other contrivance at such a height that its micrometer should be ten inches from the objective. Its reading would then give the real size of the image formed at that...
Page 200 - Further, I have elsewhere shown that the loganite is proved by its texture to have been a fragmental substance, or at least filled with loose debris ; that the Tudor specimens have the cavities filled with a sedimentary limestone, and that several fragmental specimens from Madoc are actually wholly calcareous. It is to be observed, however, that the wholly calcareous specimens present great difficulties to an observer; and I have no doubt that they are usually overlooked by collectors in consequence...

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