A guide to the microscopical examination of drinking water : with an appendix on the microscopical examination of air / by J.D. MacDonald.

Date:
1883
Catalogue details

Licence: Public Domain Mark

Credit: A guide to the microscopical examination of drinking water : with an appendix on the microscopical examination of air / by J.D. MacDonald. Source: Wellcome Collection.

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

    134/224 (page 14)
    MOVEMENT OF PLANTS AND ANIMALS. as far as we know, not a single genuine protozoon lias yet been classed by the botanist in his domain; while our greatest diffi- culty at the present time is to eliminate the protophyta from the realm of zoology. It will be scarcely doubted that the numerous species of Difflugia Arcella and Euglypha, for example, are veritable animals ; but the equally numerous naked Amosbce are so wonderfully imitated both in appearance and movement by truly vegetable Amceboids, that falling into error in relation to them might be very excusable. The following kinds of movement may be noticed and com- pared in the two kingdoms :— Protophyta. Protozoa. 'Without special organs .... Bacillus, &c Gregarina. a U) t> o 3 With special organs. . ’ By pseudopodia - By cilia . , . , By flagella . . . Amoeboids of Volvox . Spores of Vauchehia . Euglbna,&c. . . Amceba. Paramecium. Noctiluca. The pliant Vibrio and the rigid Diatom exhibit the pheno- menon of spontaneous movement, connected probably with the play of the same, or similar nutritive processes, developing dialytic currents which are on this account quite invisible, while they operate as a moving cause or movable bodies. In this way the diatom moves without change of form, and shall we say that by the same law the extensile plasma of Amccba and Amoeboid alike is drawn out into Pseudopodia, with the semblance of active and even voluntary motion ? Above the lowest grades of plants and animals, or such as are notified in the above table, no difficulty can arise in assign- ing to every form its true position; and when the Flagcllata, as a whole, are placed with the Protophyta, as in the following arrangement, nearly all the uncertainty and misunderstanding at present existing will be at once removed.