378 ON THE STUDY OF MICRO-FUNGI. 



were not infected, so they were retained as control plants ; so that 

 if the infected ones developed the secidium and the control plants 

 did not, then it would be pretty conclusive evidence that the spores 

 on the grass were the cause of the fungus on the Herb Paris. 

 Owing to some difficulties I experienced in getting the plants to 

 grow, my cultures were not successful ; but Dr. Plowright, who 

 very kindly took a deal of trouble in helping to work out its life- 

 history, was more successful, and I shall therefore give the results 

 which he obtained from his experiments. 



When infecting with the teleutospores, it is prudent to make 

 sure, by placing them in water and examining with a microscope, 

 that they are actually germinating, otherwise spores might easily be 

 used for the experiments which have already germinated. Such 

 exhausted spores would, of course, be useless for the object in 

 view. Previous, therefore, to the spores being applied to the Paris 

 plants, it was ascertained that the promycelial tubes were actually 

 being developed. In about eleven or twelve days after infection 

 spermogonia appeared on the leaves of the plants which had been 

 infected, whilst the control plants remained perfectly free from the 

 parasite. This was very satisfactory, and showed at once the 

 connection between the spores on the two different plants. The 

 grass in question {Phalaris arundinacea)^ however, forms a host 

 for several species of Puccinia^ which respectively produce secidio- 

 spores on Allium ursinmn, A nun fnaculatmn, Convallaria ??tajah's, 

 and Rhamnus frangula, and it was therefore possible that the 

 Puccinia in question might be one of these species which, in 

 addition to producing secidiospores on the already recorded host, 

 also produced them on Paris quadrifolia. 



As the Puccinia spores are in many cases so very much alike, 

 it is impossible by microscopical examination alone to identify one 

 species from another, and it is therefore necessary to cultivate the 

 various spores, and thus show which are related. The spores in 

 question on the Phalaris grass were therefore applied to Allium 

 ursinum^ Arum maculatum^ and Convallaria majalis ; but on 

 these plants they produced no aecidium. This proved that the 

 Puccinia had nothing to do with the other species referred to, as 

 it was inefficacious in producing the aecidium on all save the Herb 

 Paris, and showed that one more Puccinia had been added to 



