9 i 8 THE ANIMAL KINGDOM. 



spore has a double cyst. D. Stagnalis and D. Nitellarum live in the cells of Cham 

 and Nitella. The inner cyst-membrane to the resting-spore is spinose in the 

 former, smooth in the latter. D. Volvocis feeds on the zooids of Volvox. 



The second family of M. zoosporeae is the Gymnococcaceae. The resting-spore 

 has as usual a membrane but no cyst, and the ingesta are expelled before its forma- 

 tion. Gymnococcus forms its zoospores in a cyst \ G. Fockei is parasitic in Diatoms; 

 G. perniciosus in the cells of Cladophora, G. spermophilus in the spores of the blue- 

 green Alga Cylindrospermum. Aphilidium deformans inhabits the cells of the Alga 

 Coleochaete ; its zoospores have no cysts. Pseudosporidium lives in cultures of Algae. 

 The zoospore gives origin to a slug-like Amoeba, which may form a resting or 

 hypno-cyst and become free again. It ends by becoming globular, secreting a 

 membrane, perforated and furnished with an operculum at one spot where the 

 zoospores, to which it gives rise, escape. Protomyxa aurantiaca is marine,, and was 

 found by Haeckel on the shell of a Spirula in the Canary Islands. It forms a 

 laminated globular cyst -122 mm. in diameter, the orange-coloured contents of 

 which segment into some hundreds of uni-ciliate pyriform zoospores. The latter 

 become amoeboid ; some of the Amoebae fuse into an orange-coloured plasmodium 

 with reticulate pseudopodia which feeds on Diatoms and Peridinidae, and eventually 

 encysts again. Haeckel found no nucleus. 



The third family of M. zoosporeae is the Plasmodiophoreae. Its members are 

 parasitic in the cells of the roots of plants. The amoeba breaks up within the cells 

 into minute zoospores and there is no cyst. P lasmodiophora Brassicae infests 

 Cruriferae, especially species of Brassica ; Tetramyxa parasitica various water 

 plants. The latter is peculiar in that the Amoeba first divides into cells, and the 

 latter in turn each into four spores which remain united. It is possible that the 

 Amoeba is a plasmodium. 



M. azoosporeae. The zoocyst gives origin to amoebulae. There are three 

 families. 



The first is the Vampyrellaceae, all aquatic and feeding on living or dead 

 Algae, Fungi, Protozoa, &c. Vampyrellidium vagans is aberrant. It infests Oscilla- 

 toriae, Saprolegniae, &c., and when full fed becomes globular or oval and develops 

 a thin or thick membrane, in either case escaping as a single Amoeba. Zopf 

 places here with some doubt Spirophora (Amoeba] radiosa which feeds on Scyto- 

 nemeae. When floating it is globular, when creeping flattened. Its pseudopodia 

 are long, with a tendency to twist terminally into spirals ; they vibrate to and fro 

 (see Biitschli, Z. W. Z. xxx. p. 271). It passes into a globular resting-spore, after 

 ejecting all foreign bodies. The spore gives rise to a single Amoeba. * Haplococcus 

 reticulatus lives between the muscle-fibres of animals, especially swine. Its zoocyst 

 is globular with three or several round papilliform spots from which the amoebulae 

 (6-15) escape. The resting-spore is round or tetrahedral, but has no cyst. The 

 genus Vampyrella has seven or eight species, one of which, V. Gomphonematis, is 

 marine, and feeds on the branched Diatom Gomphonema. The other species feed 

 principally on various freshwater Algae either engulfing Diatoms, Desmids, or 

 sucking out the cell-contents of filamentous Algae by pseudopodia emitted from a 

 stout process which perforates the cell membrane. The chlorophyl of the Algae is 

 partly dissolved and changed, colouring the protoplasm red, rosy, orange, yellow, 

 or brown. V. polyblasta feeds on Euglenae. The Amoeba is large, more or less 

 but of irregular shape, with pointed pseudopodia except in V. 



