4 



On the Diseases of Wheat. 



are every where diffused. The difficulty of admitting such a 

 universal dispersion of these sporules, has induced some modern 

 philosophers to support the old exploded theory of spontaneous 

 generation. Of this theory, however, we may safely assert, in 

 the present state of human knowledge, that it involves difficul- 

 ties an hundred fold more inexplicable than any which attend on 

 the opposed theory, which teaches us that all living creatures 

 proceed from similarly organized beings, originally called into 

 existence at the fiat of the Almighty. We shall therefore con- 

 sider these minute fungi to be plants, which have proceeded 

 from, and are capable of reproducing their kind by means of 

 those minute sporules, with which direct observation has made 

 us well acquainted. 



Section II. — O/? the Bvnt, SmiH-Balls, or Pepperbrand. 

 (Uredo carie.9, Dec. Uredo foetida, Bauer.) 



The fungus which occasions this well-known and much dreaded 

 disease has hitherto been met with only in the grains of wheat. 

 Its presence is readily recognised by the peculiarly disgusting 

 odour of the infected ear. It may be detected in the young seed, 

 even in the very earliest states of the flower bud ; and when fully 

 ripe it most frequently occupies the whole interior of the grain, 

 but without bursting the skin^, so that the wheat seed retains very 

 nearly the same size and shape that it would have assumed had it 

 been perfectly sound. When examined under the microscope, 

 the Bunt- fungus is seen to consist of vast numbers of extremely 

 minute globules, of a dark-colour, and which are at first attached 

 to a mass of matted thread-like matter, analogous to what is 

 termed the spawn in mushrooms, and other Agarics — and which 

 in those plants spreads underground, and frequently occasions the 

 remarkable appearances called fairy-rings. It is not easy to see 

 this spawn of the Bunt -fungus, but the little dark globules called 

 spores, may readily be detected. They may be considered ana- 

 logous to the seed-vessels of flowering plants, and each of them 

 contains a mass of almost inconceivably minute sporules, by means 

 of which the plant is propagated. 



The reproductive powers of fungi are quite beyond our com- 

 prehension. Fries, one of our greatest authorities, has calculated 

 that a particular fungus may contain 10,000,000 sporidia.* 

 Mr. Bauer has accurately measured the spores of the present 

 species, and finds their diameter is not more than ttVo- of an inch. 



* The terms sporce, sporulce, sporidia, &c., have either been applied 

 synonymously or vaguely by different authors. The more modern practice 

 appears to be, to use sporulce for the ultimate granules analoiious to seeds ; 

 sporidia for the cases or vessels containing them ; and sporcG for an addi- 

 tional covering, which sometimes includes several sporidia. 



