CLASS ARCHIMYCETES 



21 



a diameter of 25/i. It completes its maturation by a triple expulsion of 

 chromatin from the nucleolus into the nuclear vacuole. During, or 

 shortly after, the third expulsion, the endospore pushes out a short pro- 



Fig. 11. — Synchytrium endobioticum. 1. Zoospores. 2, 3. Penetration of host cells. 

 4. Young protoplast within a hypertrophied epidermal cell. 5. Group of immature sum- 

 mer spores; the single thickened cells within the rosettes are the infected epidermal cells. 

 6. Rosette. 7. Mature summer spore. 8 to 10. Germination of mature summer spores. 

 11. Young sorus, the future walls indicated by the denser protoplasm. 12. Mature 

 zoosporangium with the fundament of the emission collar. 13 to 15. Copulation of two 

 planogametes. 16, 17. Penetration of the zygote. 18. Young hypnospore. 19. Hypno- 

 spore during maturation of the zoospore primordium. 20. Empty hypnospore. (1, 12, 

 19, 20 X 520; 2, 3, 14 to 16 X 1,270; 4, 7 to 10, 17, 18 X 270; 5 X 100; 6 X 115; 11 X 535; 

 13 X 1,110; after Curtis, 1921.) 



jection and in about 4 hours the whole content slips into the remaining 

 space of the dead host cell (Fig. 11, 8 to 10). When the number of nuclei 

 reaches the neighborhood of 32 by repeated mitotic division, the proto- 

 plasm collects to denser zones (Fig. 11, 11), regardless of the position of 



