48 



PLASMODIOPHORALES 



this species on C. vernalis in Norway in 1893 and 

 1900. and altlioua;li lie fixed, sectioned and studied his 

 material lie ])uhlished notliing but passed the mate- 

 rial on to \^'inge. In 1907 Rosenfeld (Anonymous, 

 08) discovered the fungus on C. autumnalis in 

 Sweden, and since that time it has not been reported. 

 Sorodiscus CaUitrichis has a marked effect on the 

 host. All parts of the stem except the outermost corti- 

 cal tissues and ejjidermis are attacked, and the vascu- 

 lar bundles become displaced and lie scattered about 

 in the tumors or are completely destroyed. Infected 

 cells may often enlarge to 10 times their normal di- 

 ameter, but whether or not they and adjacent healthy 

 ones are stimulated to divide by the fungus is un- 

 known. It is not improbable, however, that the galls 

 are due to both cell enlargement and cell multiplica- 

 tion. The nucleus of the host cell apparently en- 

 larges also and forms several conspicuous nucleoli. 

 So far nothing is known about the site and method 

 of infection. 



S. RADICICOLUS Cook, 1931. Ann. Mveol. 29: 321. Pis. 

 1,2. 



Cystosori one to several in a cell, usually flat and 

 disc-shaped; composed of up to 50 resting spores 



usually arranged in two layers and closely pressed 

 together; enveloped in a delicate membrane which 

 later disintegrates and frees the individual spores. 

 Resting spores oval, rectangular and jiolygonal in 

 section, 3.8-4..2 ix X 3.2-3.6 fj., with smooth walls, 

 the outer layer of which may be extended to form 

 blunt spines ; separating at maturity and giving rise 

 to zoospores in germination. Zoospores oval pvri- 

 form. 2. .5-3. .5 jj., soon becoming amoeboid. Zoospo- 

 rangia unknown. Plasmodia one to several in a cell, 

 small 15-30 /t in diameter: schizogony doubtful or 

 lacking; each producing a single cystosorus ; at ma- 

 turity cleaving into uninucleate segments or spore 

 mother cells which divide twice into four resting 

 spores. 



Parasitic in tlie roots of Giinandrops'is penla- 

 phi/lla near Pretoria, South Africa, causing con- 

 voluted, coral-like galls, 3-15 mm. in diameter. 



Cook's study of this species was based entirely on 

 prepared slides and fixed material sent by Dr. E. M. 

 Doidge from South Africa. It has accordingly never 

 been examined in the living state. Many of the criti- 

 cal developmental stages such as resting spore ger- 

 mination, fusion of gametes, schizogony, alternation 



PLATE 7 



Sorodiiciis 



(Fig. 1, 3, 9-15, 23-33 after Winge, '13. Remaining figures 

 after Cook, '31. Fig. 8 drawn from portion of a plioto- 

 graph.) 



Fig. 1. Callltilche viriudis with lunnerous galls caused 

 by .'^. Callitrichii-: 



Fig. 2. Enlarged gall. 



Fig. 3. Diagrammatic sketch of cross secticm througli the 

 root and gall of Gjinandrojinis pentaphyUa showing the 

 progressive developmental stages of parasite from the root 

 to the opposite side of tumor. S. radiciroliis. 



Fig. 4. Anteriorly flagellate zoospore or gamete. .S. rad'i- 

 cicolus. 



Fig. 5. Amoeboid stage of same. S. radicieoliis. 



Fig. 6. Fusion of gametes. S. radicicoliis. 



Fig. 7. Young binucleate Plasmodium after first division 

 of zygote nucleus. .S. rndicicoliis. 



Fig. 8. Large multinucleate plasmodium. S. toi/iVico/h.*. 



Fig. 9. Resting nucleus of plasmodium. S. CaVitrirhis. 



Fig. 10. Prophase, showing differentiation of "tropho" 

 and "idioehromatin." S. ('iillltrlchh. 



Fig. 11. Equatorial plate stage of "iiromitosis" (?). S. 

 C'allitrichin. 



Fig. 12. Similar stage from a young plasmodium showing 

 chromatin aggregated into chromosome-like bodies. S. Citl- 

 iitrichin. 



Fig. 13. Anaphase with conspicuous astral rays. S. Calll- 

 trirhis. 



Fig. 14. Late telophase showing differentiation of 

 "tropo-" and "idioehromatin." S. Cdllilrichi.i. 



Fig. 1.5. Daughter nuclei with well-marked centrosome- 

 like bodies and astral rays. .'?. CaUitrichis. 



Fig. IB. Beginning of cliiomatin discharge into cyto- 

 plasm from nucleus during chromidial stage. /S. radici- 

 foluif. 



Fig. 17. Later stage showing karyosome broken u]) into 

 granules which lie at the inner peri))hery of nucleus. iS. 

 rndicicoliis. 



Fig. 18. Final akaryotc stage with all stainable chro- 

 matin discharged from nucleus. S. rridicicoliis. 



Fig. 19. Prophase of meiosis, the so-called "garland 

 stage." S. radicicoliis. 



Fig. 20. Equatorial plate stage of meiosis with four chro- 

 mosomes. Plasmodium segmenting into spore mother cells. 

 .S'. radicicoliis. 



Fig. 21. Binucleate spore mother cell >S'. racliciciihis. 



Fig. -2-2. Second meiotic division with two chromosomes. 

 S. ratlicicohis. 



Fig. 23-24. So-called "garland" stages in S. Callitrichi.i. 



Fig. 35. Equatorial plate stage of the first (homeotypic) 

 division. S. CaUitrichis. 



Fig. 2(). Equatorial plate stages of meiosis. Plasmodium 

 cleaving into segments. S. CaUitrichis. 



Fig. 27. Paired daughter nuclei in cleaving plasmodium. 

 S. CaUitrichis. 



Fig. 28, 29. Binueleate segment of plasmodium. S'. CaUi- 

 trichis. 



Fig. 30. Four incipient resting spores resulting from 

 cleavage of two binucleate segments. Nuclei quite large. 

 •S'. Callit richis. 



Fig. 31. Mature spores with two-layered walls, the outer 

 layer merging with that of neighboring spores. S. CaUi- 

 trichis. 



Fig. 32. Young spores with outer and inner walls. .S'. Cal- 

 lit richis. 



Fig. 33. Side view of cystosorus of S. CaUitrichis show- 

 ing common enveloping membrane. 



Fig. 34. Young spore with incompletely formed walls. 

 »?. radicicoliis. 



Fig. 3.5. Surface view of small cystosorus. S. radicicoliis. 



Fig. 3(i. Spiny resting spores. S. radicicoliis. 



Fig. 37. Thick-walled resting spore broken away from 

 cystosorus. S. radicicolus. 



