PLASMODIOPHORALES 



in Soiosphaera during tlie prophases of promitosis 

 (fig. 10, 11), but they contended tliat the granules 

 are derived from the karyosome and subsequently 

 aggregate around the latter as an equatorial ring. 

 Blomfield and Schwartz (10) and Osborn ('11) 

 have figured much the same type of prophases in S. 

 J'erouicae, L. Jitnci, and »S'. suhicrranea. I.utnian 

 likewise reported the presence of chromatin granules 

 in the prophases in Plaxmodiophora. "These gran- 

 ules had been previously concentrated as a hollow 

 sphere enclosing the tropochromatin of the central 

 body" (karyosome), and as the prophases progress 

 the granules of idiochromatin separate from the 

 karyosome and form a spireme, according to I.ut- 

 nian. In Sorodiscu.i Winge also reported a separation 

 of idiochromatin and tropochromatin (fig. 13) in 

 the karyosome in preparation for division, the former 

 giving rise to a thin equatorial plate and the latter 



forming the nucleole. He believed that in the resting 

 nucleus the idiochromatin may "be partly resolved 

 in the tropochromatin. which later forms the chromo- 

 philous filaments radiating from the caryosome." 

 Cook ('26, '28) and Cook and Schwartz ('30) failed 

 to observe any marked prophase stages in Lir/niera 

 and Plasmodiophora but asserted that the peripheral 

 layer of chromatin which is present in the resting nu- 

 cleus condenses and becomes aggregated in a ring 

 around the karyosome (fig. 14). Shortly thereafter 

 the spindle fibers appear in the nuclear cavity and 

 form a fusiform intranuclear spindle (fig. 1.5) at 

 right angles to the chromatin ring, which in the mean- 

 time lias expanded and drawn away from the central 

 nucleole. Manj- of these cytologists have figured the 

 chromatin ring as a solid continuous band, but Maire 

 and Tison ('11) and Winge reported it to be com- 

 posed of numerous granules and chromosome-like 



PLATE 1 



Fifr. 1. Resting nucleus, P. Brassicae, showing wheel-like 

 structure. Prowazek, '0.5. 



Fig. -2. Resting nucleus, T. parasitico , with karyosomic 

 granules at peri])hery. Maire and Tison, '11. 



Fig. 3. Uninucleate amoeba, S. V eronicae , with centro- 

 some and astral rays. Maire and Tison, '09. 



Fig. -1. Resting nucleus, iS. siibterraiiea, with wheel-like 

 structure. Osborn, '11. 



Fig. 5. Resting nucleus, L. Juiici, with chromatin around 

 inner periphery of nucleus. Cook, '^8. 



Fig. a. Early prophase, P. Brasxicae, showing numerous 

 chromatin granules. Nawaschin, '99. 



Fig. 7. Early prophase, P. Briisslrne. showing separation 

 of idiocbromatin and tropbocliromatin in the karyosome. 

 Prowazek, I.e. 



Figs. 8, 9. Differentiation of nucleole and chromatin ring. 

 P. Brasnicue. Prowazek, I.e. 



Figs. 10, 11. Prophases, S. Vfroniciie, showing separation 

 of idiochromatin and its accumulatin on the linin. Maire 

 and Tison, '09. 



Fig. 12. Early prophase nucleus, L. Juiici, with wheel- 

 like structure. Schwartz, '10. 



Fig. 13. Separation of idio- and Irophochromatin in 

 karyosome during early prophase, S. Callitrichii). Winge, 

 '13.' 



Fig. 14. Early prophase, L. Jiinci, showing formation of 

 chromatin ring around nucleole. Cook, 'J8. 



Figs. 15, 10. "Saturn" stages of promitosis, L. Juiici. 

 Cook, I.e. 



Figs. 17, 18. "Cruciform" stages with elongating nu- 

 cleoli, L. .IiincI and T. Tri</lorh!nix. Cook, I.e.; Maire and 

 Tison, '11. 



Fig. 19. Splitting and sejiaration of chromatin ring, and 

 constriction of nucleole, L. .Tiniri. Cook, I.e. 



Fig. 20. Later stage, L. .Jiiiici, showing division of nu- 

 cleole. Cook, I.e. 



Fig. 21. "Double anchor" stage of promitosis, L. .Time!. 

 Cook, I.e. 



Figs. 22, 23. Formation of daughter nuclei, L. .Tiiiiri. 

 Cook, I.e. 



Fig. 34. Wheel type of resting nucleus, ./. iniinirohi. 

 Chatton, '10. 



Fig. 2.'). Early prophase, ./. froschi. Nagler, '09. 



Figs. 26, 27. Equatorial plate stages, ,1. lacustri'i. Nag- 

 ler, I.e. 



Fig. 28. Same stage, A. inii,iicoIa. Chatton, I.e. 



Fig. 29. Early anaphase, Vahlkiniipfia liiiiax. Calkins, 

 '33. 



Fig. 30. Later anaphase, J. frnschi. Niigler, I.e. 



Fig. 31. Similar stage, A. musicoUi. Chatton, I.e. 



Fig. 32. Telophase, A. mu.iirola. Chatton, I.e. 



Fig. 33. Reconstructed daughter nuclei, ./. froschi. Niig- 

 ler, I.e. 



Fig. 34. Wheel type of resting nucleus, Spoiif/o.iporn siib- 

 terraiien, with nucleole, radiating linin threads, and chro- 

 matin granules. Home, '30. 



Fig. 3.5. Resting nucleus, Soro.'!phaera Veronicae, with 

 eentrosomes and astral rays. Home, I.e. 



Figs. 3(j, 37. Early prophase, S. Veronicae. Webb, '35. 



Fig. 38. Same stage, P. Br<i.isicoe. Terby, '23. 



Fig. 39. Spireme stage, >S'. xiibterroiiea. Home, I.e. 



Figs. 40, 41. Late prophases, S. Veronicae, with four 

 elongate chromosomes. Webb, I.e. 



Figs. 42, 43. Later stages, 8. Veronicae. Chromosomes 

 showing prophase split. Webb, i.e. 



Fig. 44. Polar view of equatorial plate, S. Veronicae, 

 with four split, twisted chromosomes. Webb, I.e. 



Fig. 45. Early equatorial plate, S. Veronicae, with four 

 Ll-shaped chromosomes. Webb, I.e. 



Fig. 48. Equatorial plate or "Saturn-stage," S. Veroni- 

 cae, witb four chromosomes end to end in a ring around the 

 constricted nucleole. Webb, I.e. 



Fig. 47. Similar stage, P. Brasnicae. with nucleole break- 

 ing up into globules. Terby, "32. 



Fig. 48. "Saturn-stage," in S. nuhterranea with three of 

 the four chromosomes arranged in a ring. Home, I.e. 



Fig. 49. Oblique view, N. Veronicae, of same stage. Webb, 

 I.e. 



Fig. 50. Equatorial plate, P. Bra,<isicae. stained with 

 Feulgen's nuclear stain; nucleole colorless. Milovidov, '33. 



Fig. 51. Metaphase, S. Veronicae, showing start of chro- 

 mosome separation. Webb, I.e. 



Figs. 52-61. Successive anaphase and telophase stages, 

 S. Veronicae. Webb, I.e. 



Figs. ()2, 63. Formation of daughter nucleoli f rimi gran- 

 ules in telophase nuclei, P. Bra.i.iicae. Terby, I.e. 



Fig. 64. Daughter nuclei, ]'. Brasnicae, with remanent of 

 old nucleole between. Terby, I.e. 



Fig. 65. New formed nuclei, P. Brasaicae. with rema- 

 nents of old nucleoli in the cyt()]ilasm. Terby, I.e. 



