PARASITIC FUNGI. 99 



under very high powers of the microscope still some idea 

 may be formed from the above statements of the astonish- 

 ing nay incomprehensible reproductive powers of the 

 parasitic fungi which infest our farm crops. It is not to be 

 supposed, however, that all the parasitic fungi are merely 

 " pests," while under certain conditions they truly are so ; 

 they nevertheless play an important and a beneficent part 

 in the economy of nature ; for, attaching themselves to de- 

 caying matter, they hasten its decomposition, suck up its 

 juices, which would otherwise taint the atmosphere, and 

 thus act as the "scavengers of nature." "Of these parasi- 

 tic fungi, some,'' says the authority we have already quoted, 

 " are restricted to one species of plant, some to another ; 

 but, generally speaking, most of them are capable of living 

 upon more than one species of the same genus; where, of 

 course, we might expect the resemblance in all points to be 

 very close. Some fungi confine their attacks to the seeds, 

 others to the stem or leaves, and some even to one side 

 only of the leaves. One of those which attack wheat lives 

 only on the grain, another more particularly attacks the 

 short stalk (the pedicil) on which each flower is seated, 

 whilst three .... are restricted to the straw, chaff, and 

 leaves, but all five live at first beneath the epidermis, and 

 not upon it. In this respect they bear a close analogy to 

 those parasitic animals which live within the bodies of 

 other animals, some immediately beneath the skin, others 

 in the intestines, and others, again, within the very sub- 

 stance of the muscle. It is the extraordinary minuteness 

 of the sporules of these fungi which allows of their being 

 absorbed by the roots, and probably also through the pores 

 of the stem and leaves of the plants; and then they are 

 conveyed by the sap to the various parts where they are 

 enabled to germinate, grow, and fructify. The sporules of 



in preventing errors of description. "The terms sporce, sporulce, 

 sporidce, &c., have either been applied synonymously or vaguely 

 "by different authors. The more modern practice appears to be to 

 use sporulae, for the ultimate granules analogous to seed ; sporidia for 

 the cases or vessels containing them ; and sporce for the additional 

 covering which sometimes includes several sporidia. 



