50 



'LASMODIOP MORALES 



of haploid and diploid generations, ete., are thus in 

 need of further investigation. 



The method of infection has not been observed, 

 but Cook believed that the amoeboid zoospores or 

 amoebae are capable of passing through the walls 

 from cell to cell and even to the outside of the host 

 where they may infect other roots. As is shown in 

 figure 3 at least two generations of the parasite may 

 occur in large galls during the course of one season, 

 but the host plants are not seriously affected by the 

 presence of the galls and fungus. The central cylin- 

 der of the roots apparently is not attacked, and the 

 galls seem to originate in the cortex, although Cook 

 was not at all clear about their origin. Infected cells 

 do not enlarge greatly, but their nuclei eventually 

 become disorganized and degenerate. The presence 

 of the fungus may possibly stimulate cytokinesis or 

 at least does not ])revent division of infected and ad- 

 jacent healthy cells. The galls are therefore doubt- 

 less due to both cell enlargement and cell multiplica- 

 tion. 



S. KARLINGII Cook, 1933, I.e. p. 207. Karling, 1938. Am. 

 .Tour. Hot. 1.5: 485. PI. 3;?, fig. 1-9. 



Cystosori numerous, up to 400 in a cell, quite va- 

 riable in size and shape, often oval, elongate and 

 disc-shaped, 15-30 /x X 15-70 /x, occasionally almost 

 spherical, 10-35 /x in diameter, irregular, or reduced 

 to tetrads, triads, diads and rarely monads; consist- 

 ing of from 1 to 200 spores; enveloping membrane 

 unknown. Resting spores polygonal and angular, 

 •t-9 ;«., when pressed together in large sori, spherical, 

 oval and ellipsoidal when single or in small groups, 

 5-23 /J. in diameter, uni- or multinucleate with hya- 

 line smooth walls and surmounted by one and oc- 

 casionally two fairly thick caps; germination un- 

 known. Plasmodia one to several in a cell, multi- 

 nucleate, and uj) to 90 /j, in diameter; schizogony 

 unknown. Zoosporangia and zoospores unknown. 



Parasitic in Chara coniraria and C. delicatiila in 

 New York City, causing marked hypertrophy of the 

 infected cells. 



This is the only known species which parasitizes 

 algae. Because of the great variation in the size and 

 shape of its cystosori and the lack of a common sur- 

 rounding membrane, it is a doubtful member of 

 Sorodiscus, and until more is known about its life 

 cycle it is retained only provisionally in this genus. 

 Its effect on the host is quite marked and extensive, 

 and all cells appear to be equally susceptible. Hyper- 

 trophied stipules, leaflets, spicules, internodal and 

 cortical cells have frequently been found. As is 

 shown in figures 1 and 2 infected cells may swell to 

 many times their normal diameter and have the ap- 

 pearance of s))herical. oval and elongate green blis- 

 ters. 



The presence of the plasmodia has no visible effect 

 at first on the streaming of the host jjrotoijlasm and 

 are continually carried along ])assively with the host 

 nuclei and cytoplasm. Individual hypertrophied cor- 

 tical cells have been removed from the leaves and 



kept alive in hanging drops for ten days, during 

 which period the plasmodia, host nuclei and cj'to- 

 plasm rotated continually. The streaming begins to 

 slow down in about 12 days and ceases entirely 

 within 20 days, after which the cell soon dies. As is 

 shown in figure 3 the host nuclei and cytoplasm ap- 

 pear normal during the actively streaming period, 

 and in spite of the extension which it has undergone 

 the cell wall remains normal in thickness. Later, the 

 host protoplasm is reduced to a thin layer. The jires- 

 ence of the parasite mav also often lead to the for- 

 mation of an abundance of storage starch grains in 

 the plastids. 



The cystosori, which were previously ('28) called 

 sporangesori by the author, are quite variable in size 

 and shape, and those consisting of a few large multi- 

 nucleate and several small uni-nucleate spores (fig. 

 15, 21) have possibly arisen by unequal and incom- 

 plete cleavage of the plasmodium. The unusually 

 large multinucleate spores (fig. 19) are probably 

 the result of the encystment of the entire plasmodia 

 which failed to segment. Since such spores are multi- 

 nucleate, it is not improbable that they form several 

 zoospore in germination. 



ADDITIONAL BIBLIOGRAPHY: SORODISCl'S 



Anonymous. 1908. Bot. Tidsskr. -28: XXVII. 

 Cook, W. R. I. 1933. Arch. Protistk. 80: 303. 

 KareltscliikoiT, S., and S. Rosanoff. 1870. Mem. Soc. Sci. 



Nat. Cherbourg. 3nd ser. 5: 12i. 

 Palm, B. T., and M. Burk. 1933. Arch. Protistk. 79: 371. 

 Schwartz, E. .J. 1914. Ann. Bot. 38: 330. 



PLATE 8 



Sornclisrus karliiigil 



(All figures after Karling) 



Fig. 1. Hypertrophied internodal cell of C. fhlicnfiiln 

 which has burst the sheath of cortical cells. 



Fig. 3. An extreme case of parasitism of the cortical cells 

 of C. contraria. 



Fig. 3. Longitudinal section of an enlarged cortical cell 

 witli twenty-six cystosori and seven plasmodia surrounded 

 by the host protoplasm. The six host nuclei appear normal. 



Fig. 4-6'. Uni-, bi- and tetranucleate stages of the jiara- 

 site. 



Fig. 7. A multinucleate vacuolate plasmodium in surface 

 view. 



Fig. 8. Similar plasmodium in edge view. 



Fig. 9. Large irregular plasmodium. 



Fig. 10. Cleavage of plasmodium to form cystosorus. 



Fig. 11. Surface view of a large flattened cystosorus con- 

 sisting of approximately 300 spores. 



Fig. 13. An almost spherical cystosorus. 



Fig. 13. Flattened cystosorus in end view. 



Fig. 14. Tetrad of resting spores. 



Fig. 15, 1(). Further variations in size and shape of cysto- 

 sori. 



Fig. 17, 18. Small resting spores in side and surface views 

 showing the apical caps. 



Fig. 19. Large isolated multinucleate spore. 



Fig. 30, 31. Cystosori consisting of two and three spores. 



