CHYTRIDIINEAE 69 



plants. Rytz concluded that this species has but few chief 

 hosts, but in favouring weather it infects other plants. 

 In marshy land near Berne the creeping loosestrife (Lysi- 

 machia nummularid) was the chief host ; in the Bernese 

 Oberland it was Saxifraga aizoides. Some species of 

 Synchytrium are of economic importance from their infecting 

 food-plants ; the potato, the cabbage and the strawberry. 



Schroeter states that their occurrence is often very 

 regional, infected plants being abundant in one district, 

 whilst the same kind of plant in other similar regions is free. 

 Dampness of the soil favours them : in a low-lying part of 

 a meadow he found many infected scabious plants, but in 

 higher parts of the same meadow the scabious was free 

 from infection. Rytz states that Synchytrium alpimim, 

 parasitic in Viola biflora, is very common in Switzerland 

 up to 2400 metres, far above the tree limit. 



Many Synchytrians are coloured; yellow, orange, and 

 red being common. They owe their colours to lipochromes. 

 Tn the spirit in which infected leaves are kept drops of 

 coloured oil may collect at the bottom of the containing 

 vessel. 



Their effects on the host-plants vary. Often they are 

 not very damaging, causing only a nodular thickening of 

 the edges of leaves, which are rolled inw r ards. With the 

 naked eye sometimes, always with the aid of a pocket-lens, 

 the coloured or pearly points can be seen on leaf or stem or 

 both. They are sometimes obscured by hypertrophy or 



