190 ABOUT FUNGI. [CHAP. 
carted down King William Street, and a year or 
so ago an undescribed Pezzza flourished inside my 
cistern.” 
Besides the pleasure of healthy association with 
beautiful scenery obtained in searching for them, 
fungi have a claim upon our at- 
tention for other reasons. First, 
guy V. they are by no means insignifi- 
AQ cant factors in the economy of 
Nature. As we have said, they 
are parasites and scavengers. 
Much of the natural food of man 
is destroyed by these plants, and 
for this reason alone we ought 
to know something about them. 
One of the most troublesome 
fungi in this respect is Peronospora infestans, the 
Potato fungus, to which we have referred at some 
Fic. 142. 
length in Chapter I. As will be seen, on reference 
to fig. 142, it is one of the moulds, somewhat resem- 
bling Mucor. Fig. 143 shows a section of the potato 
