200 FUNGI. 



id. berberidis seemed more than ever probable. In about ten 

 days the spermogonia appeared. After a time the cut leaves 

 began to decay, so that the fungus never got beyond the 

 spermogonoid stage. Some three-year-old seedlings were then 

 taken, and the germinating resting spores applied as before. 

 The plants were kept under a bell-glass from twenty-four to 

 forty-eight hours, and then exposed to the air like other plants. 

 From the sixth to the tenth day, yellow spots appeared, with 

 single spermogonia ; from the ninth to the twelfth, spermogonia 

 appeared in numbers on either surface ; and, a few days later, 

 on the under surface of the leaves, the cylindrical sporangia 

 of the Mcidium made their appearance, exactly as in the 

 normally developed parasite, except that they were longer, 

 from being protected from external agents. The younger the 

 leaves, the more rapid was the development of the parasite, and 

 sometimes, in the younger leaves,"the luxuriance was far greater 

 than in free nature. Similar plants, to the number of two 

 hundred, were observed in the nursery, and though some of them 

 had Mcidium pustules, not one fresh pustule was produced ; 

 while two placed under similar circumstances, but without the 

 application of any resting spores, remained all the summer free 

 from JEcidium. It seems, then, indubitable so far that ^Ecidium 

 berberidis does spring from the spores of Puccinia graminis. 



It has, however, to be remarked that De Bary was not equally 

 successful in producing the Puccinia from the spores of the 

 jKcidium. In many cases the spores do not germinate when 

 placed on glass, and they do not preserve their power of germi- 

 nating very long. He reverts then to the evidence of experi- 

 ments instituted by agriculturists. Bonninghausen remarked, in 

 1818, that wheat, rye, and barley which were sown in the neigh- 

 bourhood of a berberry bush covered with JEcidium contracted 

 rust immediately after the maturation of the spores of the JEcidia. 

 The rust was most abundant where the wind carried the spores. 

 The following year, the same observations were repeated ; the 

 spores of the Mcidium were collected, and applied to some healthy- 

 plants of rye. After five or six days these plants were affected 

 with rust, while the remainder of the crop was sound. In 1863 



