The Sarcodina 229 



companied by the hypertrophy of tissues and formation of galls. A host 

 index has been published by Karling (70). The mature stage is a plas- 

 modium which may divide into small plasmodia or may give rise to 

 uninucleate cysts ("spores"). Although chitin has been reported, cellulose 

 apparently is not produced by the Plasmodiophorina. 



Fig. 5. 21. A-I. Typical life-cycle of Plasmodiophorina, diagrammatic 

 (after Cook): A. Uninucleate cyst ("spore"). B. Excystment. C. Flagellate 

 stage. D. Amoeboid stage, after loss of flagellum. E. Amoeboid stage sup- 

 posedly formed by fusion of two flagellates. F. Binucleate amoeboid stage. 

 G. Plasmodium in host cell. H. Products of plasmotomy. I. Developing 

 spores. J-M. Sporomyxa tenebrionis Rietschel (from Tenebrio moUtor), xl890 

 (after R.): uninucleate stage (J); amoeboid form with four nuclei (K); de- 

 veloping "spores" in sporocyst (L); uninucleate spore (M). 



In a typical life-cycle (Fig, 5. 21, A-I) excystment releases a myxoflag- 

 ellate in the soil. This flagellate ("swarm-cell") penetrates a cell in a 

 root-hair of the plant host and becomes a myxamoeba. Or, according to 

 some accounts (27), two myxoflagellates or two amoebae may fuse to 

 produce a diploid myxamoeba. At any rate, the myxamoeba develops 

 into a Plasmodium which, at maturity, mav undergo plasmotomy or 

 produce uninucleate cysts (Fig. 5. 21, H, I). 



