History of infusoria, including the desmidiaceae and diatomaceae, British and foreign / by Andrew Pritchard.

  • Andrew Pritchard
Date:
1861
Catalogue details

Licence: Public Domain Mark

Credit: History of infusoria, including the desmidiaceae and diatomaceae, British and foreign / by Andrew Pritchard. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

    105/1074 (page 85)
    present surface, and close npon the rock which forms the original bed of this cstuaiy, the mind is irresistibly led to the conclusion that they have existed there fi-om the time when the waters fii'st rolled over the spot. Berg-mehl, Tripoli, and other polishing-powders, the stratified deposits at Ellin in Bohemia and in ^gina, and numerous others examined and reported on by various microscopists might likewise be adduced to demonstrate the important pai-t played by these individually in^dsible beings, when accumu- lated in coimtlcss myriads, in the construction of the earth's crust. The Oolitic, and even some eai'lier metamorphic rocks, porphyritic rocks, &c., are not wanting, according to Ehi-enberg, in species of Diatomeae ; but in the Pliocene, Miocene, Eocene, and in chalk and flint, and still more in the tertiaiy deposits, the abundance and variety of forms are greater. Diato- niaceous shells are curiously preserved to us in large abundance and perfec- tion in guano, in which they have doubtless entered as a component in the way of mixture with food taken by the bii'ds which have deposited that maniu'e. The foregoing facts teach ils that probably, in the present condition of oiu* planet, no portion of its surface is destitute of Infusorial Hfe ; and now, fi'om the prosecution of microscopic research in connexion with geological facts, it would appear that, under this simj)lest and primaiy form, organic life made its fii-st appearance on the globe, and has, during the many ejjochs of this world's history, and notwithstanding the mightiest changes its surface has imdergone, been sustained until the present moment; and, what is more, so extraordinary is the capability of the silicious Diatomeae to preserve life, and so astonishing theii- powers of multiplication, that species which are now found living have theii- generic and even their specific types at the veiy daw of creation. Prof. Ehi-enbcrg has advanced this same statement in liis recent work {Milcrogeologie), saying that the oldest sUicious Infusoria, whe- ther Carboniferous or Silmian, belong to the same genera, and often to the same species. AiiEOLiTic DiATOMEJ]:.—Ehi-enberg was the first to demonstrate the fi'c- quent existence of Diatomeae along with other microscopic beings and or- gajiic particles in the atmosphere, principally in those showers of dust which fall from time to time in various parts of the world, and in those other mete- oric products Imown by the name of ' meteoric paper' and ' blood-rain.' In such atmospheric productions, the Berlin natiu'alist has detected above a hun- di-ed species; these, accompanied by descriptions and figures, and prefaced by an account of aU such atmospheric phenomena on record, were pubHshed by Ehrenberg in a lai-ge brochure entitled Passamaub uml Blutregeti consisting of 192 foUo pages. An extract from this book wiU convey the best attainable notion of the physical importance of these aerial dust-showers iho quantity of actual solid matter that ha-s faUen from the atmosphere by showers is far more considerable than supposed; for, though it falLs in a difiu-sed dust-hke fomi, the extent of surface covered at any one time is [h'^+nH!' 't .- ,^°'P^™8- ^V^'^ meteorolites, Ehrenberg observes that the total quantity of these stones which fell between 1790 and 1819 weighed wd-hlhn^v 7%0o' ■TSl;^,,t^«t-shower at Lyons, in 184G, the solid matter o hS ?l^?f^ i ? 1<l^i«t-storms in Italy, at Cape de Verd, and in Sn hSi ' ,r '^T'^'^ T'Z 'Fautity of matter Sins S f n Ehrenberg suggests to the imngination the irt^nin '^'■'^ ^^^^ '^''^ tlie time of Homer. Lastly, he Smt.Tf < ''''r' ^P^'' I'^teoric dust does not necessarily «»n. .n : f f ^i*^ ^ai'tli'« .surface, and from the force of atmospheric omunts, but from some general law of the ,itmosphcrc, according to which