MYCETOZOA 



191 



cells. The nuclei undergo mitotic division. Finally the Plasmo- 

 dium divides into a large number of simple spores. 



PlasmodiopJwra brassicae Woronin (Fig. 72). Parasitic in all 

 species of Brassica. 



Other genera are Sorosphaera Schroter, parasitic in Veron- 

 ica; Tetramyxa Goebel, forming gall in Ruppia, etc. 



'^© 



6 



I sy^. 



Fig. 72. Plasmodiophora brassicae. 

 a, root-hernia of cabbage; b, a spore (X620); c-e, stages in germination of 

 spore (X620); f, myxamoeba (X620 after Woronin); g, a host cell with several 

 young parasites (X400); h, an older parasite (X400 after Nawaschin). 



References 



DE Bary. 1864 Die Mycetozoen. Second edition. Leipzig. 

 Jahn, E. 1901-1920 Myxomycetenstudien 



Ber. 



I to X. 



Deutsch. Bot. Ges., Vols. 19, 20, 22-26, 29, 36, 37. 



Jones, P. M. 1928 Morphology and cultural study of Plas- 

 modiophora brassicae. Arch. f. Protistenk., Vol. 62. 



Lister, A. 1924 A monograph on the Mycetozoa. Third 

 edition. London. 



MacBride, T. H. 1922 North American slime moulds. Sec- 

 ond edition. New York. 



