204 DISEASES OF FIELD & GARDEN CROPS. [CH. 



additional species belonging to both genera as found in 

 the United States. The author says : " There is nothing 

 to confirm the views of Oersted as to the connection of 

 particular species." 



In reference to Podisoma Juniperi - Sabince, Fr., and 

 Rcestdia cancellata, Reb., Professor Farlow points out 

 that the former is " very common in Massachusetts, 

 whereas its supposed JEddium, R. cancellata, Reb., is not 

 known with certainty to occur at all." 



Professor Farlow experimented in 1876, 1877, and 

 1878, with the spores of Podisoma Juniper i-Sabince, Fr., 

 with the following results : 



Nine leaves were taken, three of Cratcegus (hawthorn), 

 three of Amelanchier (medlar), and three of apple. Sper- 

 mogonia appeared on the three Cratcegus leaves only. All 

 nine leaves were such as the Rcestelice grow upon naturally. 



An experiment was then made with a young plant of 

 Cratcegus. Result nothing. 



On five leaves of Cratcegus. Result nothing. 



The first experiment was repeated with three leaves of 

 Pyrus added, out of the twelve leaves spermogonia appeared 

 on the three of Cratcegus only, although Pyrus was the 

 plant pointed out by Oersted. 



Ten leaves, six Cratcegus, three pear and one apple. 

 Result nothing. 



Professor Farlow also records that not only did he get 

 spermogonia on the leaves of Cratcegus tomentosa, L., after 

 the application of the spores from Podisoma Juniperi-Sabince, 

 Fr. ; but he got a like result from the application of the 

 spores of Gymnosporangium biseptum, Ellis, and G. macro- 

 pus, Lk., both fungi being peculiar to America, one ex- 

 tremely rare, and both unknown in Europe. On Pyrus, 

 the genus especially pointed out by Oersted, there was 

 invariably no result. Sometimes the spermogonia appeared 

 suspiciously early, as in four days, Oersted gave nine or 

 ten, and sometimes the uninfected control plants also 

 exhibited spermogonia. Mr. Plowright mentions eighteen 



