1 6 THE NORTH AMERICAN SLIME-MOULDS 



THE MYXOMYCETES (Link} De Bary. 



Chlorophyl-less organisms whose vegetative phase consists 

 of a naked mass of multinuclear protoplasm, the plasmodiuin ; 

 reproduced by spores which are either free or more commonly 

 enclosed in sporangia, and which on germinating produce 

 ciliated or amoeboid zoospores, whose coalescence gives rise to 

 the plasmodium. 



The Myxomycetes are either 



A. Parasites, in the cells of living plants . . . PHYTOMYXIN^E 

 or 



B. Saprophytes, developed in connection with decaying vegetable matter : 



a. With free spores ...... EXOSPORE^E 



b. With spores in receptacles or sporangia . . MYXOGASTRES 



SUB-CLASS PHYTOMYXIN^ Schroeter. 

 1889. PhytomyxincE Schroeter, Engl. u. Prantl, I. i., pp. i and 5. 



The parasitic Myxomycetes include but few (four or five) 

 species, distributed among four genera. They are all parasites 

 in the cells of living plants ; their vegetative phase is plasmodial, 

 and their spores are formed by the simultaneous breaking up 

 of the plasmodium into an indefinite number of independent 

 cells. But a single genus need here concern us, 



Plasmodiophora Woronin. 



1879. Plasmodiophora Woronin, Pringsh. Jahrb., XL, p. 548. 



Parasitic in the parenchymatous cells of the roots of living 

 plants : causing noticeable enlargement of the affected organ, 

 producing at length galls, knots, and various deformities and 

 distortions. Spores spherical, smooth, colorless, i6/A. 



i. PLASMODIOPHORA BRASSIC^E Woronin. 



1879. Plasmodiophora brassica Woronin, I.e. 



This species, the only one so far reported in this country, 



