110 



ROYAL HORTICULTURAL SOCIETY. 



In a first series of experiments, seven leaves were used on the 

 31st of May. On the 9th of June numerous yellow spots ap- 

 peared on five of the leaves, which under the microscope were 

 found to be filled with spermogonia exactly as in the common 

 ^Ecidium Berheridis. Two days later they were studded with 

 numerous spermogonia. 



Four summer shoots from a tree which had a few scattered 

 jEcidium pustules were attended with precisely the same results. 

 For comparison, a number of healthy leaves quite free from JEci- 

 dium were taken and no Buccinia-sipores applied, and not the 

 slightest trace of spermagonia appeared. 



After a time the cut leaves always began to decay, so that the 

 fungus never got beyond the sperm agonoid stage. Some three years 

 old unbranched seedlings were therefore taken, and the germi- 

 nating 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 spermagonia ; from the 

 ninth to the twelfth, spermagonia appeared in numbers on either 

 surface, and a few days later on the under surface of the leaves ; 

 the cylindrical sporangia of the JEcidium 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 

 200, were observed in the nursery, and though some of them had 

 JEcidium-yxistxiles 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 

 JEcidiim. 



It seems, then, indubitable so far that ^Ecidium Berheridis does 

 spring from the spores of Puccinia graminis. 



It is, however, to be remarked that our author has not been 

 equally successful in producing the JPuccinia from the spores of 

 the JEcidiwn. In many cases the spores do not germinate when 

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

 nating at all very long. He reverts, therefore, to the evidence of 

 experiments instituted by agriculturists. Bonninghausen re- 

 marked, in 1818, that wheat, rye, and barley which were sown in 

 the neighbourhood of a barberry bush covered with JEcidium con- 

 tracted rust immediately after the maturation of the spores of the 



