Mycological Notes 11. 



By 

 C. Ferdinandsen and 0.Winge. 



A. Danish Fungi. 



Phycomyceteae. 



Cladochytrium Myriophylli Rostr. 

 Myriophyllum verticillatum L. 



Our material of the above fungus, described by Rostr up in ,Myk. 

 Medd." IX, Bot. Tidsskr., 26. Bd., p. 305, was collected by Mag. N. 

 Hartz in a slough near Holte, Sealand (Sept. 1908)^) and sent to 

 the Botanical Museum in Copenhagen. We placed the Myriophyllum- 

 plant in question with its turions and tumours, occasioned by the Clado- 

 chytrium, in a cylinder-glass by room-temperature for the purpose of 

 studying the development of the fungus, which was not further investi- 

 gated by Rostr up. — In the following our observations are given in 

 chronological order. 



1908 Sept. 17. — On macroscopic examination of transversally cut 

 young tumours are seen figures, occasioned by the enclosed spores; the 

 spore-filled parts namely are brown and thereby distinct from the sur- 

 rounding tissues. Microscopically the structure of the tumours is the fol- 

 lowing (transverse section) : The epidermis consists of one cell-layer, 

 beneath which is seen a nCortex" of slightly thick-walled, somewhat tangen- 

 tially stretched cells, stuffed with starch. Beneath this cortex lays a thin- 

 walled, amylaceous parenchyma with vascular bundles. In this tissue the 

 mycelium of the fungus appears, being outmost slender and perishable, 

 ^/s — 1 fi thick; it pierces the thin cell-walls and produces numerous 

 swellings. The mycelial swellings consist either of a single, terminal 

 vesicle or of two, the proximal one of which is thin-walled and peri- 

 shable, sending out a number of filaments, while the distal one becomes 

 big and stuffed with oil-drops (either small and regular drops of equal 



') All the plants of Myriophyllum, growing in the slough, were infested by 



the fungus. 



