SYNCH YTRIUM 



99 



so that eventually, cells that formed the peripheral or outside 

 row are deeply buried in the tumour, and resting-spores are 



Fig. 20. Synchy triii in solani ; Black scab of potato. 



consequently met with buried deeply in the flesh of the 

 tumour. It will be observed, however, in examining a section 

 of a wart or tumour, that the oldest and most perfectly 



