‖ plasmodium Biol.
(plæzˈməʊdɪəm)
Pl. -ia. Rarely anglicized plasmode (ˈplæzməʊd).
[mod.L. (1863, Cienkowski in Pringsheim Botanik III. 400), f. plasma + -odium: see -ode1.]
1. A mass or sheet of naked protoplasm, formed by the fusion, or by the aggregation, of a number of amœboid bodies (true plasmodium or fusion-plasmodium, pseudo-plasmodium or aggregation plasmodium), and having an amœboid creeping movement.
First observed as one stage in the life-history of the Myxomycetes or Mycetozoa, the position of which as vegetable or animal organisms is disputed; also in certain groups of Protozoa, and other simple animal forms.
| 1875 Encycl. Brit. III. 693/2 The formation of the plasmodium is a kind of complex conjugation. 1875 Bennett & Dyer Sachs' Bot. 276 Myxomycetes... The swarm-spores cease dividing and unite, two or more of them coalescing—after they have gone over into the Amœba form—into a homogeneous protoplasmic substance, also endowed with an Amœba-like motion, the Plasmodium. 1875 Allman in Phil. Trans. CLXV. 561, 571. 1877 Huxley Anat. Inv. Anim. ii. 81 A certain number of the myxopods unite together, and become fused into an active plasmodium, which exhibits no trace of their primitive separation. 1880 Geddes in Proc. Royal Soc. XXX. 252 On the coalescence of Amœboid cells into Plasmodia. Ibid. 254 The formation of plasmodia was at first supposed to be peculiar to the Myxomycetes, but several Rhizopods have been described in which a more or less complete cell-fusion has been observed... All the evidence points to the conclusion that the power of coalescing with its fellows, under favourable circumstances, to form a plasmodium, is..a very widely spread, if not a general property of the amœboid cell. 1882 Vines Sachs' Bot. 263. 1888 Rolleston & Jackson Anim. Life 912 Fusion to form plasmodia recurs in some Proteomyxan Monadineæ, as to the animal nature of which there can be no doubt. 1890 Cent. Dict., Plasmode, same as plasmodium. |
2. Name given to certain parasitic organisms found in the blood of patients with recent malaria, and quartan and tertian ague.
Discovered by Laveran (1880), and named by him, as a vegetable organism,
Oscillaria malariæ; referred by Marchiafava and Celli to the animal kingdom, and called by them (1885)
Plasmodium malariæ; more recently distinguished as belonging to two genera of Protozoa,
Laverania and
Plasmodium. (Minchin in Ray Lankester
Treatise on Zoology i. ii. 243 (1903).)
| 1895 in Syd. Soc. Lex. 1897 Allbutt's Syst. Med. II. 724 Marchiafava and Celli described with great accuracy the intra-corpuscular amœboid form, to which they gave the name plasmodium. 1898 P. Manson Trop. Diseases i. 2 note, The malaria parasite is not a plasmodium in the zoological meaning of the word. 1899 Allbutt's Syst. Med. VI. 595 The most careful examination of the blood during the paroxysms showed no evidence of plasmodia. |
| attrib. and Comb. 1898 P. Manson Trop. Diseases ii. 37 It has been considered advisable to expunge the term remittent fever as indicative of a distinct species of plasmodium disease. Ibid. 49 The plasmodium-infected corpuscles. Ibid. iii. 86 A protective, plasmodium-destroying agency inherent in the human body. Ibid. vi. 116 Plasmodium-like organisms. |
Hence
plasˈmodial,
plasmodic (
-ˈɒdɪk)
adjs., pertaining to, of the nature of, or arising from, a plasmodium;
plasˈmodiate a., having or characterized by plasmodia, as the
Mycetozoa;
plasˈmodiate v. intr., to become fused into a plasmodium;
plasmodiˈation, formation of a plasmodium;
plasˈmodiocarp [
Gr. καρπός fruit], an irregular-shaped fructification occurring in the
Myxomycetes (hence
plasˌmodioˈcarpous a.).
| 1892 J. A. Thomson Outl. Zool. 109 The *plasmodial stage in the cycle is predominant. 1896 Allbutt's Syst. Med. I. 542 Malaria (which is due to plasmodial infection and is not a bacterial disease). |
| 1882 A. S. Wilson in Gard. Chron. XVII. 671 The application of moisture to a spore..is directly seen to cause it either to give birth to a zoospore, or to *plasmodiate, retaining its contents. |
| Ibid., A manure..of a hygrosorptive character is just the very manure to promote the *plasmodiation of these spores, and render them fit to be absorbed in the form of a fluid plasm by the roots of the plants. |
| 1877 M. C. Cooke Myxomycetes Gt. Britain 30 (Contrib. to Mycologia Britann.) *Plasmodiocarp. 1899 Knowledge 1 May 116/1 Plasmodiocarp is a term applied to the spore-bearing part when it is sessile and irregular in form, sometimes like a cushion, sometimes like..a long tube. |