SYNCHYTRIUM 



101 



ciliate zoospores, 3-4 /x in diameter in some instances, 

 escaped directly into the water of the hanging-drop, whereas 

 in other instances, the inner hyaline wall of the resting- 



o 





FIG. 21. Synchytrium solani. i, section through portion 

 of a young potato sprout, showing many of the peripheral 

 cells infected by the zoospores of the fungus. The central cell 

 that is dividing has escaped infection ; 2, section through a 

 portion of a scab, showing mature resting-spores deep down 

 in the tissue and the youngest at the periphery ; 3, a 

 young resting-spore not yet enclosed in a thick wall ; 4, 5, 

 and 7, mature resting-spores ; 6, a resting-spore germinat- 

 ing, i-ciliate zoospores escaping. All highly mag. 



spore, containing the zoospores, was extruded, the zoospores 

 eventually escaping into the water. The epidermal cells are 

 infected by the zoospore, which at first forms a naked mass 

 of protoplasm that gradually increases in size, then becomes 

 invested with a thin, colourless wall, upon which is eventually 

 laid down a thick, brown, smooth, stratified, chitinous wall. 



