A SERIOUS LETTUCE DISEASE. 
103 
Fig. lib. These increase until the whole filament becomes very vacuo¬ 
late, and finally all apparently coalesce to one large vacuole which 
nearly fills the whole of the cell, Fig. 11c. 
The attachments first appear as numerous short branches from near 
the tip of an ordinary hypha. Each one of these primary off-shoots 
produces branches that again branch forming a rather compact mass, 
Fig. 12. They are at first continuous but very soon become septate. 
Fig. 15.—Germ tubes from ascospores producing gonidia. 
With the appearance of the septa the tips of the branches enlarge. 
When they come into contact with some solid as a culture dish or a 
lettuce leaf, they become somewhat flattened, Fig. 13, on the end and 
apply themselves to and cohert to the substance. 
Gonidia .—Frequently both in drop and in plate cultures there are 
found small spherical bodies, gonidia, that appear very much like 
spores, Fig. 14, although they have never been seen to germinate. 
They are highly refractive bodies, measuring about 2 to 3 mu in 
diameter, and are produced in large numbers in acropetal succession 
upon flask-shaped stalks. These stalks are produced either as lateral 
branches of an ordinary vegetative hypha or as the termination of 
