PROTOMYXA. 



[ 641 ] 



PROTOZOA. 



spores : a filament with several spores in 

 course of division appears like a varicose 

 tube ; it is septate, however ; and when the 

 globular spores are mature, they have a 

 double coat; in P. macrosponts the diameter 

 of the ripe spore is about 1-5000". When 

 advanced in age, the mycelium appears to be 

 whollv converted into spores, which become 

 free. The existence of these Fungi is ren- 

 dered more or less evident externally by 

 w.irtv projections of the epidermis, finally 

 bursting. Unger describes four species P. 

 macrosponis occurring on JEyopodium and 

 Angelica, P. endoyenus (Galii) occurring on 

 Gcdiuin mollugo, P. microsporus on Ranun- 

 culus repens, and P. Paridis on Paris qua- 

 dnfolia. De Bary found a species on Me- 

 ni/anthes, with oval spores 1-800" long- and 

 1-1300" broad. A species (P. cancomitaw) 

 has lately been found on exotic Orchids. 



BIBL. "linger, Exanthem. d. Pftanz, 341 ; 

 Da Bary, Brandpilze, 15, pis. 1 & 2, and 

 Beitmge,\. 1864; Leveille, Ann. So. Nat. 3. 

 viii. 374; Tulasne, ibid. vii. 112; Fries, 

 Sum. Veq. 517. 



PROTOMYX'A, Haeckel. A genus of 

 Protista. 



Char. A simple shapeless mass of proto- 

 plasm, with vacuoles, which protrudes rami- 

 fying and anastomosing pseudopodia. Re- 

 production by zoospores, forming plas- 

 modia. 



Protomyxa aurantiaca, orange-red ; resting 

 condition globular, with a thick structure- 

 less covering. Zoospores pear-shaped, with 

 a strong flagellum at the pointed end, at first 

 moving like the zoospores of the Myxo- 

 mycetes, afterwards creeping like an Amoeba. 

 On empty shells of Spinda ; Canary Islands. 

 (Haeckel, Gen. Morph. ; Bronn, Klass. fyc.) 



PROTOMYXOMY'CES, Cunn. A 

 genus of Myxomycetes. P. coprinarius, in 

 the intestines of man, cows &c. ; amoeboid 

 bodies not uniting. (Cunningham, Qu. 

 Mic. Jn. 1881 ; Kent, Inf. 472.) 



PROTOPLASM. The name applied by 

 Mohl to the colourless or yellowish, homo- 

 geneous or granular viscid substance, of 

 nitrogenous constitution, which constitutes 

 the formative substance in the contents of 

 vegetable cells, in the condition of gelatinous 

 strata, reticulated threads, and nuclear aggre- 

 gations &c. It is the same substance as that 

 termed by Dujardin in animals SARCODE. 



Protoplasm is the simplest form which 

 organized matter can assume, and which, 

 without any other material peculiarities 

 except a certain softness, transparency, and 



jelly-like condition, is capable of contracting, 

 expanding, and assimilating. It is common 

 to the animal and vegetable kingdoms. 

 See CELL, SARCODE, and PRIMORDIAL 



UTRICLE. 



PROTOSPON'GIA, Kt A genus of 

 Choano-flagellate Infusoria. Ovate, imbed- 

 ded in a gelatinous matrix ; flagellum single. 

 P. Haeckelii ; length 1-3000' ; freshwater. 

 (Kent, Inf. 363.) 



PROTOZO'A. A Subkingdom of the 

 Animal Kingdom, characterized by the 

 absence of distinct organs, the form and 

 simple organization being reduced to those 

 of a cell (Siebold). If the above definition 

 be adopted, it must be remembered that the 

 cell may be represented by the cell-contents 

 only ; and these we believe to constitute the 

 essential part of a cell (see Edition 1856), 

 which is now generally admitted. 



The Protozoa form the lowest group of 

 the Animal Kingdom. They are mostly 

 minute, and aquatic, consisting of a mass of 

 gelatinous protoplasm or sarcode. This is 

 usually granular, often containing minute 

 globules of fat, sometimes minute crystalline 

 particles. Sometimes one or more nuclei 

 are present, often they are absent. The body 

 is naked in some, in others it is enveloped 

 in a carapace or shell, which may be simply 

 membranous, calcareous, as in the Forami- 

 nifera, or siliceous, as in the Polycystina and 

 AcanthometrcB. Movement is effected by 

 pseudopodia, which are short and stout, or 

 long and slender, processes of the protoplasm, 

 sometimes branching and anastomosing to 

 form meshes or plasmodia ; by cilia ; or by 

 flagelliforni filaments. There is no proper 

 gastric cavity. The food-particles are in the 

 lowest forms entangled and brought to the 

 body by the pseudopodia, as in Amceba and 

 Actinophrys &c., or ingested from all parts 

 of the surface ; while in many Infusoria there 

 is a distinct mouth and anus. Contractile 

 vesicles supposed to represent a circulatory 

 apparatus are sometimes, but not always 

 present. Reproduction is produced by fission, 

 by conjugation, or by the breaking-up of the 

 nucleus. 



The Protozoa approach closely the lower 

 and simpler forms of the Vegetable Kingdom ; 

 and very different views are held as to the 

 characters by which they may be distin- 

 guished, and the organisms which belong to 

 the two kingdoms. 



An older character was, that animals 

 subsist upon ingested organized matter, 

 while plants prepare their food from un- 



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