ON THE STUDY OF MICRO-FUNGI. 377 



host plant and part upon another host plant of a totally different 

 species. For instance, Puccinia obsaira dwells during the aecidium 

 stage on the common Daisy {Bellis percn?iis), and during the Uredo 

 and Puccinia stages on the Field Woodrush {Luzida campestris). 

 Fungi of this nature are termed heteroecious, and they will not 

 develop unless the necessary two host plants are present. For 

 instance, the latter two stages could not be produced on the Daisy, 

 neither could the former stage be produced on the Luzula. When 

 the aecidiospores on the Daisy are ripe, they fall down upon, or 

 are blown on to, any specimens of Luzula campestris that may be 

 near at hand, where they germinate and produce in the ordinary 

 way the mycelium, which eventually gives rise to the uredo and 

 teleutospores. These last-named spores develop, in like manner, 

 when they find a resting-place on the Daisy leaves and produce 

 the secidiospores. This strange and peculiarly interesting feature 

 was therefore the clue which had to be followed in the search for 

 the missing links in the history oi Vadium paradis , as it appeared 

 highly probable that the species was heteroecious. I was unable to 

 follow up the quest that same year, but when opportunity served 

 an investigation of the plants growing in proximity to the Herb 

 Paris was made, and though there were several other species of 

 fungi close at hand, yet they were well known and had nothing to 

 do with the one in question. But just over the place where the 

 young Paris plants were raising their heads from the soil, a con- 

 siderable quantity of dry, withered Canary Grass {Phalaris arun- 

 dinaced) of the last year's growth was lying upon the ground, and 

 this grass was covered with very minute black spots, which on 

 examination proved to be little beds of fungi, Puccinia. This 

 discovery at once gave rise to what proved to be a well-founded 

 suspicion: that these spores were the very ones that were required, 

 but the only way in which the truth could be definitely ascertained 

 was by actually taking the spores and endeavouring to produce 

 from them the secidium on the Herb Paris. 



A number of Paris plants, which were just beginning to unfold 

 their leaves, were therefore collected from a place where it was 

 considered they were in all probability free from the disease, and 

 some of the spores from the canary grass were placed upon the 

 leaves of several of them. One or two of the plants, however, 



International Journal of Microscopy and Natural Science. 



Third Series. Vol. V. bb 



