PYCNOCHYTRIUM. Ill 



as zoospores swarming by means of a ciliuni. In acUlition, 

 resting-spores are developed singly or in groups. 



The first effect on the host-cell of the entrance of a swarm- 

 spore is that it becomes distinctly larger. At the same time 

 neighbouring cells are so stimulated that they multiply and 

 form a prominent ring-shaped swelling. The sporangia discharge 

 their zoospores on the host-plant itself, and these pass into 

 other cells of the swelling ; here they form resting-spores and 

 the host-cells die. Schroeter states tliat the resting-spores may 

 1)6 found from August onwards. 



S. stellariae, Fuck. On Stellaria media and S. nemorum. 

 The reddish-yellow her. ^spherical swellings are produced on leaves, 

 stems, flower-stalks, a .d sepals, either isolated or as a crust. 

 The resting-spores ger'^rally form brown crusts. The host-leaves 

 may be somewhat c^ Ipled, but beyond this undergo little de- 

 formation.^ 



' Chrysochytrium. 



( 1 ) Forming simple vesicles : 



Synchytrium myosotidis, Kiihn (U. S. America). Tlie t\)\- 

 denaal cells when attacked swell up to form club-shaped 

 processes, while the cells with no fungus remain unaltered. 

 The normal hairs of the host-plant are fewer on diseased than 

 on healthy parts. This parasite attacks IJoragineae, c.y. Myoxofis 

 ■stricfa, LifJiosj)crnnim arvcnsc. 



S. cupulatum, Thomas, produces red eruptions on Pot cat ill o 

 arffcntid and Driias ocfoprtala ; diseased cells of tlie host-plant 

 contain red sap. 



S. punctum, .Sorokiu. On I'lanfafp lanccoJata and P. nmliK. 



S. laetum, Schroet. On Gagca. 



(2) Forming compound vesicles : 



S. aureum, Schroet. Attacks many herbaceous plants as well 

 as leaves of many shrubs and trees. Frequent on Lysimdchin 

 Niommnlaria, Fragaria, etc. The cells attacked are swollen and 

 enclosed in a patch of enlarged neighbouring cells. 



S. pilificum, Thomas. On Potent'dla TormcntUIa. The 

 vesicles are hemispherical, and bear on their summits a tuft 

 of abnormally elongated hairs. Thomas- found this species 



1 Clendeniu {Botanical Gazette, 1894, p. 296) describes and figures a Si/nchy/rhm 

 on Stellaria media in America (Edit.). 



-Ber. d. di'utsch. hotan. Ges., 188.3, p. 496. 



