WIXGE, CYTOLOG. STUDIES IX THE PLASMODIOPHORACEJE. 23 



each spore of the aggregation, notwithstanding the size of 

 the af^f^resation, is able freelv to send out its contents at the 

 germination. As mentioned below this is in Spongospora 

 practised in the most beautiful manner by air-channels in 

 the spore-cysts. In Plasmodiophora the spores are collected 

 into massive aggregations, but are not so solidly connected 

 here as in the other genera. 



Sorodlscus Lagerh. et Winge gen. nov. 



Genus Plasmodiophoracearum. Sporae earum generis 

 Sorosphaera similes sunt. Sporosori autem coacervatione spo- 

 rarum diversi, placentas, quae ex duobus stratis constant, 

 circuitu irregulari formantes. 



Sorodiscus Callitrichis Lagerh. et Winge sp. nov. 



I. Statu vegatativo myxamoebae plurinucleatae ple- 

 rumque plures in singulis cellulis hospitis per fungum maxime 

 auctis jacent. Divisionibus earum mitosibusque propriis nuc- 

 leorum generationes plures genitae sunt. 



II. Statu fructifero myxamoebae in amoebulas uni- 

 nucleatas partiuntur. Nucleis amoebularum se bis mitotice 

 dividentibus — divisione secunda numero chromosomarum 

 dimidiato — amoebulis quoque bis se dimidiantibus, amoe- 

 bulae uninucleatae, se prostremo in sporosoros coacervantes, 

 formatae sunt. Sporae aseptatae, fere hyalinae, crasse tuni- 

 catae, urnuliformes, apice vallo orbiculato coronatae; multae 

 axis parallells in placentam duplicem, i. e. placentam duobus 

 stratis formatam, circuitu irregulari plerumque oblongam con- 

 veniunt. Sori circiter 20—30 [j. lat., sporae 6 — 7 |x X 4 — 5 u.. 



In caulibus Callitrichis vernalis tumöres globosos plerum- 

 que 2— 4 mm. diam. efficiens. Ad Maalselvdalen, Tromsoe 

 Norvegiae (collegit G. Lagerheim). Adhuc praeterea in 

 C. autiininali in Suecia et Russia inventus. 



Spoiigospora siibterraiiea (Wallroth) Johnson. 



In 1886 Brunchorst^'' described as Spongospora Solani 

 an organism which causes the disease in potato tubers, known 



