278 



experiments with Uredinales; experiments which would have roused 

 the greatest sensation if they had then been pubhshed, but which 

 have now been repeated later on by others. The reason for which 

 they were not published then, must be ascribed to the fact that P. 

 Nielsen had to interrupt these experiments to deal with other things 

 which completely filled his time. I have made great efiforts to find 

 some diary or account of these experiments, but in vain, so most of 

 this information is owing to the notes in P. Nielsen's herbarium. It is 

 quite sure that Nielsen must have made a much greater number of 

 experiments than those stated below, he must especially have made 

 many experiments in vain, as, by that time, only a few of the rela- 

 tions, now familiar, were known. He himself has described his pro- 

 ceeding (77 b ^), it is quite like that of the uredinologists of the pre- 

 sent time. P. Nielsen himself has only given very scanty information 

 of his cultivating experiments (77 a &. b), and Rostrup also gives very 

 scattered and brief accounts of them (R 82 b, 83 d '"'\ 84 a, 89 b). 



Coleosporium. 



P. Nielsen's herbarium contains Coleosporium sp. on Campanula 

 trachelium &. rapunculoides, Senecio vulgaris, Sonchus arvensis &. 

 asper, Alectorolophus and Tussilago all produced by sowing of spo- 

 res of Peridermium pini acicola in 1879—80—81 ; further informations 

 is wanting. 



Klebahn later on repeated a number of these experiments in 1892 

 in ignorance of the results of P. Nielsen. 



Melampsora. 



1879 P. Nielsen infected Populus alba &. tremula with caeomaspores 

 from Mercurialis perennis and vice versa, repeated 1880 and 

 1881, confirmed by Rostrup's experiment (see R 82 b "">, 83 d^"^ 

 6. 84 a ''). 



1879 infected Ribes with hibernated teleutospores from Salix undulata 

 &. molissima and the following year vice versa (see R 83 d ^'", 

 84 a, 89 b "'). 



1880 infected Salix cinerea with caeomaspores of Melampsora evonymi- 

 caprearum Klebahn (see R 84 d). 



1880 infected Populus tremula with caeomaspores from Corydallis cava 

 and vice versa 1883 (17 years before Bubak). 



Uromyces. 



1874 infected Poa trivialis with aecidiospores from Ranunculus ficaria" 

 &. repens, and again 1877-78 (see P. N. 77 a "). 



