Dale. — On the Cause of ‘ Blindness * in Potato Tubers . 
131 
Summary. 
The mycelium of Verticillium albo-atrum is present in c blind ’ potato 
tubers, where it causes the destruction of most of the c eyes ’. It grows up 
into the new shoots, when any are formed, and in some cases it may pass 
into the subaerial shoots. In other cases it never goes beyond the sub- 
terranean stems and creeps along them into the newly-formed tubers, 
internally as a colourless mycelium in the cortical tissues, and externally as 
a scanty thin brown mycelium. Thus the tubers may be infected by means 
of the vegetative mycelium only, without the formation of any kind of spore. 
The course of the fungus from the old to the new tuber may be traced by 
means of the brown coloration of the affected tissues. Tubers have been 
grown in three successive years from the original diseased crop, and in each 
year some have been blind and have had a warty and corky outer surface. 
School of Agriculture, 
Cambridge. 
October , 1911. 
