CO129-538-2 Hong Kong University 23-6-1932 - 15-3-1933 — Page 90

123

38

W. R. IVIMey Cook,

diameter. Spores produce multinucleate amoeba which develop into plasmodia. From plasmodia fresh spore-balls are formed. The organism causes tumours on the roots of Campanula rapunculoides. It has only been found on a single occasion in a garden near Sora in Holland,

Genus 5. Tetramyxa Göbel.

Göbel, K. Flora. Vol. 67. Pp. 517-521. 1884.

Spores aggregated into packets of four, which on germination give rise to amaboid swarm spores which fuse in pairs and migrate into the young tissues of the host.

1. T. parasitica Göbel. (Pl. 17, fig. 1).

Göbel, K. Flora, Vol. 67. Pp. 517-521. 1884.

Spores are 3.5 in diameter frequently arranged in tetrads, a con- dition which is readily lost owing to the absence of a common membrane around them. Spores on germination give rise to swarm spores which fuse in pairs producing plasmodia. Frequently swarm spores are devoid of flagella and after liberation become amaboid. Many spore tetrads originate from the same plasmodium, and it is during the differentiation of the spore mother cells that the tetrads are initiated. The swarm spore which infects fresh plants is not known, through those which infect fresh cells of the same plant have been observed.

The organism causes tumours in the stems of the host plants which It has been found in Ruppi may measure up to 15 mm. in diameter. rostellata, Zannichellia polycarpu and Z. palustris in France (4), and in Ruppia rostellata in Great Britain.

+

(4) Maire, R. and Tison, A. Nouvelles récherches sur les Plasmodiophoracées

Vol. 9. Pp. 226-246. 1911.

Genus 6. Ligniera Maire & Tison.

cells.

Ann. Mycol.

Maire and Tison, A. Comptes Rendus Acad. Sci. Paris, Vol. 152,

P. 206. 1911.

Spores not arranged in a definite spore-ball, but free in the host Plasmodia when On germination spores give rise to plasmodia. mature produce fresh masses of spores. In addition to the production of spores plasmodia may give rise to zoosporangia in which up to about eight roospores develop. Zoospores fuse in pairs and give rise to fresh plasmodia, Two species are recognised.

1. L. Junci (Schwartz), Cook. (Pl. 17, fig. 2).

Schwartz, E. J. Ann. Botany. Vol. 24. Pp. 511-522.

1910.

Cook, W. R. Ivimey, Trans. Brit. Mycol. Soc. Vol. 11. Pp. 196-213-

1926.

1910.

Syn. Sorosphæra junci Schwartz, E. J. Ann. Botany, Vol. 24. Pp. 551-522.

Sorosphæra graminis Schwartz, E. J. Ann. Botany. Vol. 25. Pp. 791-797, 1911. Ligniera radiculis Maire, and Tison, A. Ann. Mycol, Vol. 9. Pp. 226 246. 1911.

Vol. 16. Pp. 136- Sarolpidium beta Nemec, B. Bull internat. de l'Acad. Sci. Boliême.

144. 1911.

The Hong Kong Naturalist.

The Hong Kong Naturalist Supplement.

No. 1.

Plate 17, figure 1.

Tetramyza parasitica, Spores x 320.

Plate 17, figure 2.

Ligniera Junci. Spores x 320.

PRINTED BY 5.C.M. POST,

124

Page 90Page 91