THE PROTEOMYXA 



which have been studied by other observers than their original 

 discoverers, no defined nuclei have been found. 



A considerable number of genera are parasitic upon freshwater 

 algae during at least one stage of their life-history, such as Vam- 

 pyrellidium, F'ampyrella, Leptophrys, Endyonema, Enteromyxa, Col- 

 podella, Pseudospora, Gymnococcus, Aphelidium, Tetramyxa, and 

 Ectobiella. Tetramyxa causes the formation of gall-like growths 

 on Ruppict and other freshwater 

 plants. Bursulla occurs in horse- 

 dung. Haplococcus occurs in the 

 muscles of the pig, but is appar- 

 ently harmless. The only species 

 that is of any economical import- 

 ance is Plasmodiophora brassicae, 

 Woronin, which attacks turnips FIO. i. 



and Causes the disease known as Ectotnella plaUaui. A, a specimen attack- 



,/T-T j rr\ JTT i >; ing Licmophora ; ps, the pseudopodium that 



" ingersand IOCS, Or "Hanbunes. is pushed into the substance of the host; v, 



A rrmsirW-iblp nnmbpr nf 0-pnpra the vacuole formed by the host containing 



A C OI genera granules pro duced by the digestive action 



are not parasitic and feed upon of the pseudopodium. B, tiie biflagiiate 



, , . zoospore of Ectobiella. (Alter de Bruyne.) 



minute animal and vegetable 



organisms. Such genera are Gymnophrys, Biomyxa, Protomyxa, 



Gloidium, and others. 



In the vegetative condition the body emits pseudopodia. These 

 pseudopodia may be roughly arranged in three categories. 



In Protamoeba, Gloidium, Enteromyxa, etc., the pseudopodia are 

 usually lobate like those characteristic of the genus Amoeba. 



In F'ampyrella, Colpodella, Monobia, Myxastrum the pseudopodia 

 are radiate in position, very delicate and rarely anastomosing, like 

 those of an Actinophrys. 



In Biomyxa, Gymnophrys, Penardia they are delicate and anasto- 

 mosing, like the pseudopodia of the Foraminifera. 



In Endyonema, Haplococcus, Aphelidium,, and other endoparasites 

 the form of the body is adapted to the spaces of the host and true 

 pseudopodia are not formed. 



In Protomyxa, Myxastrum, Protomonas, Bursulla, Plasmodiophora, 

 a. number of amoebulae unite to form a plasmodium, and it is 

 possible that plastogamy also occurs in F'ampyrella, Leptophrys, and 

 some others. In Monobia a number of stellate individuals unite to 

 form an open network (Fig. 4). 



A contractile vacuole does not usually occur in Proteomyxa, 

 but it appears to be a constant feature in Gloidium and Ciliophrys. 

 Non-contractile vacuoles occur in many of the genera. 



Although very little is known about the life -history of the 

 Proteomyxa, it seems probable that they all, at some time, form 

 .cysts or spores. In Plasmodiophora the protoplasm of the plasmodium 

 breaks up into a large number of simple spores, which are able to 



